Claudia detectives search East Yorks house

Around 20 officers were at the property in Ellerton, about 15 miles from Miss Lawrence's home in York.

A spokeswoman for North Yorkshire police said the searches were carried out yesterday and on Monday and involved an underwater team, who searched culverts which form part of the property.

"The searches are as a result of a recent development within the investigation, enquiries are continuing and no arrests have been made."

The spokeswoman was unable to confirm reports that items had been removed from the house for forensic analysis.

Miss Lawrence was last seen walking near her Heworth Road home after finishing work at the university's Goodricke College on March 18 last year.

The chef spoke with family and friends that evening but did not turn up for work the following morning.

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

One of the biggest recent developments emerged in March when detectives revealed Miss Lawrence had told a friend she had been out with a mystery boyfriend until the early hours of March 17, 2009 – the day before she was last seen alive.

The mystery boyfriend is yet to be traced.

Family spokesman Martin Dales said: "It is encouraging to know that the investigation is continuing.

"Quite what it leads to or what will happen we are obviously yet to find out, we have been here before.

"The good thing is the police are still getting these leads, everyone just wants Claudia home.

In March, detectives launched a four-day operation to search land around a mile from Miss Lawrence's workplace following a tip-off from the public.

Specialist search teams of officers combed an area of land known as The Outgang in Heslington.

Officers said "nothing of significance had been located", however, but urged members of the public to come forward with any new information about her disappearance "no matter how insignificant".

North Yorkshire Police has commissioned the National Policing Improvement Agency (NPIA) to carry out an external review of the case, with a team of investigators expected to report back in June.

It is the second such investigation into the force with the previous inquiry having praised the force's "integrity and objectivity".