BRITISH detectives working on the Madeleine McCann case are still pursuing “critical” leads as the 10th anniversary of her disappearance approaches.

Metropolitan Police Assistant Commissioner Mark Rowley said there are “significant investigative avenues” of “great interest” to both the UK and Portuguese teams.

Officers have sifted through 40,000 documents and looked at more than 600 individuals since 2011. In an interview nearly a decade after the youngster’s disappearance, Mr Rowley confirmed that four people considered as possible suspects in 2013 have been ruled out.

Madeleine vanished from the family’s holiday flat in Praia da Luz in Portugal on May 3, 2007, when she was three years old.

Her parents, Glasgow-born Gerry McCann and his wife Kate, , of Rothley, Leicestershire, have vowed to “never give up” hope of finding their daughter.

Asked if police were any closer to solving the case than six years ago, when the UK investigation began, Mr Rowley said: “We have a significant line of inquiry which is worth pursuing, and because it’s worth pursuing it could provide an answer, but until we’ve gone through it I won’t know whether we are going to get there or not.

“Ourselves and the Portuguese are doing critical work and we don’t want to spoil it by putting titbits of information out publicly.”

He declined to expand on the nature of the working theories or reveal whether any suspects were being considered, saying that disclosing further detail would not help the investigation.

Mr Rowley said: “We have got some critical lines of inquiry. Those link to particular hypotheses but I’m not going to discuss those because those are very much live investigation.

“We have got some thoughts on what we think the most likely explanations might be and we are pursuing those.”

He described the possibility of a “burglary gone wrong” as a “sensible hypothesis” which has not been “entirely ruled out”.

The officer was asked about the theory of a sex predator being responsible for Madeleine’s disappearance.

Mr Rowley said: “That’s been one key line of inquiry. The reality is in the modern world in any urban area if you cast your net widely you will find a whole pattern of offences. You will find sex offenders who live nearby.

“And those coincidences need to be sifted out, what’s a coincidence and what may be linked to the investigation that you are doing.

“Offences which may be linked have to be looked at and either ruled in or ruled out.” He said there was still a “lot unknown” in the case, adding: “All the different hypotheses have to remain open.”

Police have looked at more than 600 individuals who were identified as being potentially significant to Madeleine’s disappearance.

In 2013 the team identified four people as suspects in the case. Interviews and searches were carried out but no evidence was found to implicate the four in the disappearance.

Mr Rowley said they are no longer the subject of further investigation and have been ruled out of the inquiry.

His team continues to receive information on a daily basis. Mr Rowley said: “Thousands of pieces of information have come forward, some useful, some not, but among that have been some nuggets that have thrown some extra light on the original material that came from the time.

“That’s one of the things that’s helped us make progress and have some critical lines of inquiry we want to pursue today.”

He said there was no “definitive evidence” as to whether Madeleine is alive or dead. He added: “That’s why we describe it as a missing person inquiry. We understand why, after this many years, people will be pessimistic, but it’s important we keep an open mind.”