Students, aid workers, doctors and as many as 80 children were among the 298 people who perished when flight MH17 was apparently shot out of the sky.
Ten Britons, including a student at a Yorkshire university, were confirmed as having died in the incident over Ukraine on Thursday.
Pressure on Moscow has intensified amid growing evidence that pro-Russian separatists were behind the tragedy.
The British Government joined the United States in blaming the rebels as police disaster experts from the UK prepared to help the Dutch authorities repatriate the dead.
A Downing Street spokeswoman said: “The growing weight of evidence suggests that MH17 was shot down by a surface to air missile and that this was fired from near Torez, in territory controlled by the separatists.
“This is backed up by claims made by separatist leaders on social media, and later removed, to have shot down an aircraft that they thought belonged to the Ukrainian military.
“On this basis we assess that, without compelling information to the contrary, it is increasingly likely that MH17 was shot down by a separatist missile.”
US President Barack Obama called the attack “an outrage of unspeakable proportions”, saying he would ensure “the truth is out”.
The human cost of the tragedy began to unfold yesterday as the identities of some of
those who lost their lives on the flight – which had left Amsterdam bound for Kuala Lumpur – emerged.
Leeds University student Richard Mayne was on his way to study maths for a year at the University of Western Australia in Perth when the Boeing 777-200 came down.
The 20-year-old’s father, Simon, from Leicestershire, said: “We are beyond devastated. It is such a beautiful sunny day but our lives have been torn apart.”
Another victim was Loughborough University student Ben Pocock, who was also due to study in Australia.
Glenn Thomas, 49, a Press officer for the World Health Organisation and a former BBC journalist from Blackpool, was one of the numerous passengers who were due to attend an Aids conference in Australia.
Two Newcastle United supporters – John Alder and Liam Sweeney – were travelling to New Zealand for the club’s pre-season tour. Irish mother-of-two Edel Mahady was also on board.
As well as the Britons there were 154 Dutch passengers, 45 Malaysians, including 15 crew, 27 Australians, 12 Indonesians, four Germans, four Belgians, three Filipinos and one Canadian on board.
Mr Obama said a US national was on board.
Australian couple Irene and George Burrows, who lost a son and daughter-in-law on the Malaysian Airlines jet that disappeared in March, suffered further anguish after it was revealed more of their relatives were on board flight MH17.
The Prime Minister described the catastrophe as an “absolutely appalling, shocking, horrific incident”
that “cannot be allowed to stand”.
At an emergency meeting of the UN Security Council called by Britain, the UK’s ambassador, Sir Mark Lyall Grant, called for
Moscow to issue an “unequivocal condemnation” of the rebels’ actions.
He said without Russian support the armed groups would “wither” and claimed three Russian citizens were leading figures in the separatist Donetsk People’s Republic.
Sir Mark said: “Russian officials have claimed that armed separatists in eastern Ukraine represent a spontaneous local insurgency. We know that this is not the case.
“We know that the three leading figures of the so-called Donetsk People’s Republic are Russian citizens and have come from outside Ukraine. We know that weapons, equipment and logistical support has been systematically provided to armed separatist groups by Russia.”
The United Nations Security Council called for a “full, thorough and independent investigation.”
• A LEEDS University student with a “great thirst for life” was among the ten Britons aboard the flight when it crashed.
Rugby union player Richard Mayne had just finished his second year studying maths and finance at the university.
He was originally from Leicestershire and his former headteacher at The Dixie Grammar School, in Market Bosworth, John Wood, said the school community was “devastated.
Mr Mayne had been a member of its title-winning rugby team and deputy head boy.
Mr Wood said he last saw Mr Mayne, who he described as “extremely pleasant and thoughtful”, just a month ago, when he talked “excitedly” about his charity fundraising trip to Everest Base Camp earlier this year.
He added: “Richard had a great thirst for life and he wanted to make the world a better place. It is tragic that his life has been cut short, especially under these circumstances – he had such a great future ahead of him.”
Mr Mayne’s Facebook page features pictures from the Everest trip, aimed at raising money for the charity Kidasha, which supports disadvantaged and vulnerable children in Nepal.
Writing on his JustGiving page, Mr Mayne said: “A BIG thank you to everyone supporting this cause and helping me to reach the £3,000 which will change the lives of so many children!”
The trip was arranged by Leeds University’s Raise and Give (RAG) Society, who tweeted: “We are deeply saddened to hear of the death of RAG member Richard Mayne on board MH17. Thoughts and sympathy are with his family and friends.”
A spokesperson from the University of Leeds said: “We are very saddened to hear the news that one of our students, Richard Mayne, is believed to be a passenger on the flight. Our thoughts are with Richard’s family and friends.
“Richard had just finished his second year in maths and finance and he was doing well with his studies. Staff are working with the university’s counselling service to help students who are affected by this tragedy and we will do all we can to support them.”
Ten Britons are now known to have died aboard flight MH17, Malaysia Airlines confirmed.
Glenn Thomas, a media relations co-ordinator for the World Health Organisation (Who) in Geneva, also died in the crash. The 49-year-old former BBC journalist from Blackpool was travelling to an international Aids conference in Australia.
Who spokeswoman Fadela Chaib said: “We have lost a wonderful person and a great professional. Our hearts are broken. We are all in shock.”
Newcastle United supporters have left floral tributes at the club’s ground to two fellow followers who also died in the crash.
John Alder, in his 60s, and Liam Sweeney, 28, were travelling to New Zealand to watch their team play in a pre-season tour.
The club said both men were familiar faces at every United away game and attended reserve and academy matches as well as first-team games.
Newcastle United manager Alan Pardew said that his players were “deeply shocked and saddened” by the news.
He said: “We all knew how passionately John and Liam supported the team and the club. They were with us just earlier this week for our first pre-season friendly against Oldham and their dedication to travel all the way around the world to support us in New Zealand tells you all you need to know about the passion they had for Newcastle United.”
Ben Pocock, a second year international business degree student at Loughborough University, was also among the British victims. He was on his way to Australia to study abroad as part of the third year of his degree.
The university paid tribute to Mr Pocock, from Bristol.