Video: Kathryn wins Oscar's battle of the exes

The film-maker also won the battle of the exes at the US ceremony, with her Iraq war drama The Hurt Locker also winning best film and a total of six awards compared with three for former husband James Cameron's 3D epic Avatar.

Bigelow's best director gong was greeted with loud cheers from the star-studded audience in Los Angeles.

The 82nd Academy Awards also saw bookies' favourite Jeff Bridges scoop best actor for country and western flick Crazy Heart, and Sandra Bullock win best actress for her role in The Blind Side.

It meant Britain's best acting nominees and main Oscar hopes Colin Firth, Dame Helen Mirren and starlet Carey Mulligan went home empty-handed.

Bigelow looked surprised to receive best director and appeared to be shaking with emotion by the time the best picture award was read out.

She said on receiving the directing award: "This really is, there's no way to describe it.

"It's the moment of a lifetime."

She said she had admired the work of many members of the audience for decades.

Bigelow praised the screenplay as "courageous".

She said: "I would not be standing here if it wasn't for Mark Boal, who risked his life for the words on the page."

Bigelow also paid tribute to soldiers still fighting.

She said: "I would like to dedicate this to the people who risk their lives on a daily basis in Iraq and Afghanistan....may they come home safe."

Both Avatar, which has become the biggest-grossing film in history, and The Hurt Locker came into the awards with nine nominations each.

Receiving the best picture gong, Bigelow said she wanted to make "perhaps one more dedication to men and women all over the world who, sorry to reiterate, who wear uniform, but even, not just the military... firemen, they're there for us and we're there for them."

An elated Bridges shouted: "Mum and Dad, yeah look - woo-hoo!"

He said: "Thank you Mum and Dad, for turning me on to such a groovy profession.

"Oh my dad, my mum, they love showbiz so much. I can remember my mum getting all of us kids to entertain at parties. I can remember my dad sitting me on his bed and teaching me all off the basics of acting... They love showbiz so much and I feel an extension of them.

"This is honouring them as much as it is me."

Before the award was announced, speaking on stage Michelle Pfeiffer described Bridges' role as "the performance of a lifetime".

Bullock, a first-time nominee, praised her fellow shortlisted actresses in her thank-you speech.

She asked the audience: "Did I really earn this or did I just wear you all down?

"I would like to thank the Academy for allowing me in the last month to have the most incredible ride with rooms full of artists that I see tonight and that I've worked with before and I hope to work with in the future, who inspire me and blaze trails for us.

"Four of them that I've fallen deeply in love with I share this night with and I share this award with."

She said of Precious star Gabourey Sidibe: "Gabby, I love you so much. You are exquisite. You are beyond words to me."

Turning to 24-year-old An Education actress Mulligan, she said: "Carey, your grace and your elegance and your beauty and your talent makes me sick."

Of Dame Helen, who was in the running for The Last Station, she said: "Helen, I feel like we are family through family and I don't have the words to express just what I think of you."

And addressing Oscars veteran Meryl Streep, Bullock said: "You know what I think of you and you are such a good kisser...

"I thank you so much for this opportunity that I share with these extraordinary women and my lover Meryl Streep. Thank you."

The Hurt Locker, made for a fraction of Avatar's budget, also won the original screenplay award for Boal, as well as picking up gongs for sound editing, sound mixing and film editing.

Avatar won prizes in the technical categories for visual effects, cinematography and art direction.

Hard-hitting movie Precious did well at the awards, with one of the most memorable acceptance speeches of the ceremony from Mo'Nique, for her role in the hard-hitting film Precious.

Fighting back tears, she thanked the Academy "for showing that it can be about the performance and not the politics".

She also paid tribute to her "amazing" husband Sidney Hicks for his advice, adding "sometimes you have to forego doing what's popular in order to do what's right - and baby you were so right.

"God bless us all."

Precious also won the adapted screenplay award, beating Armando Iannucci's In The Loop writing team as well as Nick Hornby for An Education.

It was mostly a night of disappointment for the Brits, a far cry from last year's ceremony, which saw Slumdog Millionaire dominate the awards.

An Education, based on the memoirs of journalist Lynn Barber, failed to take any gongs home, despite receiving three nods.

Christoph Waltz won the best supporting actor award for playing a bloodthirsty Nazi in Inglourious Basterds.

Waltz said: "Everybody helped me find a place."

He paid tribute to director Quentin Tarantino and continued: "There's no way I can ever thank you enough. But I can start right now, thank you."

One British hope who did manage to triumph was Sandy Powell, who took home her third Academy Award for costume design on The Young Victoria.

Powell joked: "I've already got two of these at home so I'm feeling greedy."

She dedicated the gong to designers on low budget and contemporary films, saying: "This one's for you but I'm going to take it home tonight, thank you."

Nick Park's Wallace and Gromit caper A Matter Of Loaf and Death was beaten in the animated short film category by Logorama.

Park arrived at the ceremony wearing a huge green bow tie, which he told Sky1 he had fashioned himself.

He told how he had created the piece of fashion attire in his kitchen with elastic and a "bit of wrapping paper".

He added: "I hope there's no Oscar regulations about the size."

Up won the animated feature film category, beating Fantastic Mr Fox among others.

Michael Giacchino also took home the prize for original score for the movie.

He sent out a message to the younger generation as he accepted the prize, saying: "Listen to me: If you want to be creative, get out there and do it. It's not a waste of time. Do it. OK? Thank you."

Bullock also received the dubious honour of receiving a "razzie" award for the worst female performance for All About Steve, at another ceremony in Los Angeles.

The Golden Raspberry Awards are dished out annually to celebrate the worst in film ahead of the Oscars, and unusually, Bullock appeared in person to pick up the gong.

Wearing a sheer silvery Marchesa dress decorated in a leaf design to the Oscars, Bullock had appeared laid-back as she insisted on the red carpet that she was "ready to relax and have a good time... Whoever's winning the statue tonight, just be there for them and have a great time."

Such was the strength of feeling that Bridges was going to win for his Crazy Heart performance that his friend and fellow best actor nominee George Clooney conceded defeat before the ceremony had even begun.

Clooney told Sky1 on the red carpet: "I feel very lucky to be here and fairly aware of the idea that Jeff Bridges is going to win.

"I love Jeff, he's my friend, so it's kind of great."

Crazy Heart also bagged the original song gong, for theme tune The Weary Kind, by Ryan Bingham and T Bone Burnett.

Best foreign language film went to Argentinian movie The Secret in Their Eyes (El Secreto de Sus Ojos).

Mulligan, who was joined on the red carpet by her proud mother, led the fashion parade with a funky strapless black gown adorned with jet black jewels.

Dame Helen wore a sheer silver number - the colour of choice among many stars - with Bigelow also opting for a metallic grey floor-length gown.

The event at the Kodak Theatre in Los Angeles was hosted by Alec Baldwin and Steve Martin, who kicked the show off with a round of cheeky quickfire gags targeting the cream of Hollywood.

Baldwin joked of 16-times nominated Streep: "No matter what, they nominate Meryl Streep."

Martin pointed out "Damn Helen Mirren" in the audience.

Baldwin corrected him, indicating at the autocue: "See, that's Dame Helen Mirren."

The ceremony opened with a singing routine from actor Neil Patrick Harris and an array of scantily-clad showgirls.