Kate and Gerry McCann also revealed they intended to challenge a court ruling clearing a Portuguese former police officer of breaching libel laws.

Speaking to the BBC's Fiona Bruce on Friday, the Leicestershire couple said they took heart from the "real progress" in the case.

The Metropolitan Police revealed last week they were pursuing “critical leads” to find Madeleine.

VOW: Kate and Gerry McCann promised to do 'whatever it takes' to find Maddie
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She went missing aged three from a holiday apartment in Praia da Luz in Portugal on May 3, 2007.

And Kate, 49, said she was no less hopeful of finding Madeleine than she had been in the weeks after she went missing.

Maddie would now be 13 and Daily Star Online revealed what she might look like now.

Kate said: “We just have to go with the process and follow it through – whatever it takes for as long as it takes.

“There is still hope that we can find Madeleine."

During the interview, Gerry, 48, acknowledged it was "devastating" not to have found Madeleine.

"We are still looking forward, I think that's the most important thing – we still hope," he said.

The McCanns said they intended to continue a legal battle against former detective Goncalo Amaral, who wrote a book about their daughter's disappearance.

Amaral had wrongly claimed in a 2008 book that Maddie had died in the family’s holiday flat in Praia Da Luz and her parents faked her abduction to cover up the tragedy.

He was ordered to pay Kate and Gerry £430,000 plus interest in damages after losing round one.

But this decision was reversed by appeal judges in April last year.

In the interview, the couple also commented on the impact of social media criticism of them, urging people to think twice before posting hurtful comments.

Gerry said: "I'm sure it is a very small minority of people who spend their time doing it, but it has totally inhibited what we do."

MYSTERY: Madeleine McCann has been missing for 10 years

"Personally, we don't use social media, although we have used it in Madeleine's campaign," he added.

"But for our twins who are growing up in an era where mobile technology is used all the time, we don't want them not to be able to use it in the same way that their peers do."

Kate described the actions of some people online as shocking but said she preferred to focus on the support many more people had offered.

"Actually the main thing that we have experienced is the goodness of people and the support that we have had over 10 years, which hasn't wavered in all that time," she said.

Asked how the McCann "family unit" had managed to stay strong during the hunt for Madeleine, her mum said: "What people do say is that you don't realise how strong you are until you have no option.

"And I think that's very true. Obviously massive events like this cause a lot of reaction, a lot of trauma and upset.

"But ultimately you have to keep going – and especially when you have got other children involved.

"Some of that is subconscious I think – your mind and body just take over to a certain extent.

"But if you can't change something immediately, you have to go with it and do the best that you can."