British detectives have a 'significant' line of inquiry in the Madeleine McCann case, ten years after the youngster went missing.

Scotland Yard chief Mark Rowley said there are still 'critical' leads that are of 'great interest' in the investigation into the three-year-old's disappearance from a holiday apartment in Portugal on May 3, 2007.

He also ruled out that Madeleine's parents Gerry and Kate McCann were involved in her abduction and said she could still be alive.

But described the possibility of a 'burglary gone wrong' as a 'sensible hypothesis' which has not been 'entirely ruled out'.

Scotland Yard Assistant Commissioner Mark Rowley (left) has said there is a 'significant line of inquiry' in the investigation into the 2007 disappearance of Madeleine McCann (right)

Madeleine's parents Kate and Gerry McCann said in a statement today that they would never give up hope of finding out what happened

The comments came after the McCanns released a statement saying they still hold out hope of finding out what happened to their daughter.

In an interview nearly a decade on from her disappearance, Metropolitan Police Assistant Commissioner Rowley ruled out Madeleine's parents as possible suspects.

He said: ‘The parents’ involvement: that was dealt with at the time by the original investigation by the Portuguese.

'We’re happy that’s completely dealt with and there is no reason whatsoever to re-open that or start rumours that’s a line of investigation.

'The McCanns are the parents of a missing girl and we’re trying to get to the bottom of what happened.’

Mr Rowley 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.'

The officer added that however Madeleine left the apartment, she was abducted.

'She wasn't old enough to make a decision to set off and start her own life,' he said.

The McCanns released the statement on their Official Find Madeleine Campaign page today

Madeleine (left) went missing nearly 10 years ago - a picture was released in 2012 of how she might have looked, aged nine (right)

Mr Rowley also revealed that detectives were pursuing new information regarding the youngster's disappearance.

He said: 'I know 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 a critical piece of 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 currently being considered, saying that disclosing further detail would not help the investigation.

Mr Rowley said: 'We've 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've got some thoughts on what we think the most likely explanations might be and we are pursuing those.'

British police officers searched a area of land in the resort in 2014 but failed to find any leads

The continued investigation has caused a backlash from locals, with this graffiti scrawled on walls in the resort in 2014

The senior 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... 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 currently doing.

'Offences which may be linked have to be looked at and either ruled in or ruled out.'

Mr Rowley 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.

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

Her parents, from Rothley in Leicestershire, have vowed to 'never give up' hope of finding their daughter.

The McCanns were staying at this apartment block in Praia De Luz, Portugal when Madeleine went missing while the couple dined nearby

The parents have said they are braced for half-truths and downright lies on social media

British officers have sifted through some 40,000 documents and looked at more than 600 individuals since 2011.

In 2013, the Met Police 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.

Meanwhile, police working on the case continue to receive information on a daily basis.

Mr Rowley said: 'Thousands of pieces of information have come forward, some useful, some not, but amongst 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.'

The assistant commissioner pledged that the investigation team will do all they can to provide an answer for Madeleine's parents.

British detectives in Praia da Luz in 2014. Met chief Mark Rowley has admitted they may never find out what happened to her

He said: 'I so wish I could say we will definitely solve it but a small number of cases sadly don't get solved.

'What I've always said on this case, and I've said it to Kate and Gerry as well, we will do everything reasonably possible to try and find an answer.

'I just can't quite guarantee it. It always hurts that you can't guarantee success but we will do everything we reasonably can do to try and get there.'

Around 30 detectives were working on the UK probe, Operation Grange, when it was established in 2011. The team has now been scaled back to four detectives.

Last month the Home Office confirmed £85,000 was being given to the inquiry to cover operational costs from April to September. More than £11 million has been spent on the inquiry so far.

Mr Rowley insisted the investigation has achieved 'an awful lot'.

He said: 'I think people get seduced perhaps by what they see in TV dramas where the most complex cases are solved in 30 minutes or 60 minutes. What we started with here was something extraordinary.

'We've achieved a complete understanding of it all. We've sifted out many of the potential suspects, many of the people of interest and where we are today is with a much smaller team focused on a small number of remaining critical lines of inquiry that we think are significant.'

Asked about the cost of the investigation, he said: 'Big cases can take a lot of resources and a lot of time.

'We've tried to be careful about public money and as we've started with that massive sifting we've reduced the number of resources and the funding's reduced accordingly.

'But we will stick with it as long as the funding's available and as long as there are sensible lines of inquiry to pursue.'