Claudia detectives search land near York University

North Yorkshire Police said the operation in the Heslington area of the city is expected to last up to three days and followed information received over the past few days.

Miss Lawrence, 36, has been missing for her home in York for more than a year and police are treating her disappearance as a murder inquiry.

In a statement, the force said: "Police investigating the disappearance of Claudia Lawrence are conducting searches in an area of York known as 'The Outgang' which is in the Heslington area.

"The searches, which began on Tuesday March 23, are expected to take up to three days."

The spokesman added the search was not related to an appeal issued last week about Miss Lawrence's whereabouts on the evening of March 16 last year when she was said to have spent the night with a mystery date.

The York University chef was said by a friend and work colleague to have told him she was out with a boyfriend until at least 4.30am on March 17 last year – the day before she was last seen alive and only 90 minutes before she was due in work for an early morning shift.

On the eve of the first anniversary of her disappearance, it also emerged she had been having an affair for several months with a man who had a long-term partner at the time she vanished.

Police urged anyone with information about these two men to come forward to assist their inquiry.

Miss Lawrence was last seen on the afternoon of March 18 last year, walking near to her Heworth Road home after finishing work.

She spoke with family members and friends that evening but did not meet a friend for a pre-arranged drink and then failed to turn up to work at the University's Goodricke College the following morning.

Police upgraded the inquiry to a murder investigation the following month.

Claudia: The search

The timeline of Claudia's last known movements and the subsequent investigation since her disappearance:

2009

MARCH 18

5.57am - Miss Lawrence is captured on CCTV arriving for work at the University of York's Goodricke College.

2.31pm - The chef leaves work to walk the three miles to her home on Heworth Road. A female colleague sees her as she drives past in her car and gives her a lift, dropping her off outside her house.

A short time later, Miss Lawrence leaves her house and walks past the Nags Head pub. She has a brief conversation with a woman with a pram.

3.05pm - The last sighting of Miss Lawrence as she walks back to her house.

8.10pm - Miss Lawrence has a telephone conversation with her father, Peter, and then another with her mother, Joan.

8.23pm - She sends a text message to a friend.

9.12pm - Miss Lawrence receives a text on her mobile phone but it is not known if she read the message.

MARCH 19

6am - Miss Lawrence fails to arrive for her shift at work.

Later in the evening, Miss Lawrence fails to keep an arrangement to meet her friend, Suzy Cooper, at the Nags Head pub. Ms Cooper discovers her friend did not attend work and rings Mr Lawrence, who contacts North Yorkshire Police.

At some point during the day, Miss Lawrence's mobile phone is either switched off or loses power. Police have not traced it.

MARCH 23

Mr Lawrence, a solicitor from Slingsby, North Yorkshire, makes an emotional appeal for information about his daughter at a news conference at Fulford Road police station in York. He describes Miss Lawrence's disappearance as a "living nightmare".

MARCH 25

Detective Superintendent Ray Galloway, who is leading the investigation, says he believes Miss Lawrence may have come to harm after meeting someone she knew. He confirms there are now upwards of 100 police officers involved in the search and says North Yorkshire Police are bringing in officers from other forces to help.

CCTV footage of the chef's last known movements are released.

MARCH 30

Mr Galloway makes an appeal for information on BBC1's Crimewatch programme, which leads to some "very interesting calls" from members of the public.

APRIL 7

Mr Lawrence holds his first weekly press conference at his home in Slingsby, and appeals for anyone protecting his daughter's possible abductor to come forward.

APRIL 16

Police say they are investigating "significant" new lines of inquiry, including a couple seen arguing near a car on Miss Lawrence's route to work the day after she was last seen and a two men apparently trying the front door to her house in the week before she disappeared.

APRIL 17

The body of a woman is found in the River Ouse, at Bishopthorpe Bridge, in Fulford, York, but police confirm it is not Miss Lawrence. The body is later revealed to be missing 68-year-old Doncaster woman, Pauline Armitage.

APRIL 24

Detectives say they are now treating Miss Lawrence's disappearance as a suspected murder investigation and Crimestoppers offers a 10,000 reward for information leading to the conviction of those responsible.

APRIL 29

Mrs Lawrence releases her first statement through police describing her daughter's disappearance as "every parent's worst nightmare".

MAY 15

Police release CCTV footage of a man seen near Miss Lawrence's home in the early hours of March 19. Mr Galloway says the number of searching officers has been scaled-down and police are now only carrying out intelligence-led searches.

JUNE 2

A reconstruction of Miss Lawrence's last known movements and possible witness sightings is screened on BBC1's Crimewatch programme. The show also includes previously unseen footage inside Miss Lawrence's home, home videos and photographs of the chef. Miss Lawrence's sister

Ali speaks publicly for the first time as part of the programme.

Mr Galloway tells the programme that Miss Lawrence was involved in relationships of "complexity and mystery" and appeals to anyone who had ever been in a relationship with the chef to come forward.

JUNE 17

Police search the Nags Head pub, near Miss Lawrence's home on Heworth Road, but say no arrests have been made.

JUNE 26

100 days since Miss Lawrence was last seen.

Mr Lawrence takes the search worldwide with the release of a YouTube video appeal.

JULY 10

Police break down the door of a house near Miss Lawrence's home to conduct a search of the property.

AUGUST 4

Police search a run-down property on East Parade, near to Miss Lawrence's home.

AUGUST 19

Police say an external review of the investigation by the National Policing Improvement Agency (NPIA) is "extremely positive" and the force are acting upon a list recommendations.

SEPTEMBER 18

Six months since Miss Lawrence was last seen, detectives reveal they have extended their investigation to Cyprus.

2010

MARCH 18

Police reveal Ms Lawrence spent the night with a mystery boyfriend just two days before she went missing. It was "critical" they spoke to the man, a detective added.

MARCH 24

Detectives search an area near York University following new information