The mother of missing Madeleine McCann has revealed that she privately returns to the Portuguese resort where her daughter disappeared to "walk those streets" and "look for answers".

Ahead of the seventh anniversary of her daughter's disappearance, Kate McCann told the BBC that she returns "quietly" to Praia da Luz at least once or twice a year to feel close to her eldest daughter.

Madeleine, then aged three, went missing on May 3 2007 from a holiday apartment in the Algarve village as her parents dined at a nearby tapas restaurant with friends.

Asked if she would return to Praia da Luz, Mrs McCann said: " I do go back. I haven't been since last April but I do go back for personal reasons. I might once or twice a year."

She went on: "It's difficult because we don't want to go back and generate publicity because I know that local people don't like that... and, while we have some really good friends in Praia da Luz, I know some people would like it to go away.

"So when I go to Praia da Luz, I go quietly."

Asked if the visits were a chance to be close to Madeleine, Mrs McCann said: " It is - that was the last place we were with Madeleine, and I'll still walk those streets and I guess try look for answers. It helps me."

Asked what she and husband Gerry would do to mark the seventh anniversary of Madeleine's disappearance , she said: "We usually have a small gathering in the village, which we've done the last so many years."

But she added that it was Madeleine's birthday, which comes shortly afterwards and would see her turn 11, that was more difficult.

Mrs McCann's comments came as she backed a revamped alert system triggered when missing children are kidnapped or their lives are at risk - known as Child Rescue Alerts.

She said: ''When a child is abducted, families are devastated and entire communities are torn apart. The agony of not knowing where your child is is almost impossible to imagine. The helplessness is at times overwhelming.

''But there is now something we can all do to help. Please sign up to receive alerts - you could save a child's life.''

She also spoke of how she would prefer to know the truth about what happened to her daughter, even if it is ''the worst-case scenario''.

She told The Sun: ''If it was down to not knowing, or finding out news that isn't what you want to hear? At the end of the day I can't change that. What would you rather?

"I'm not under-estimating the blow of hearing bad news that your child has been killed, because obviously we're not going to go 'OK, at least we know'. But I've spent hours thinking about that and, each time, I still come up thinking we need to know. Regardless, we need to know.''

She went on: ''But there is always the worst-case scenario. That's always been a possibility and anyone who thinks that we're blinkered doesn't know us.''

The new system will allow alerts to be issued via text, email, social media, digital billboards and to the media.

Members of the public can already sign up to receive alerts, although the new system will come into play on International Missing Children's Day on May 25.

A Child Rescue Alert was recently used in the hunt for murdered five-year-old April Jones, and the system is designed to make the most of the ''golden hours'' after a child goes missing.

Charlie Hedges, from the National Crime Agency, who helped co-ordinate the appeals, said: ''The success of Child Rescue Alert is down to each and every one of us. I've already been encouraged by the wide range of organisations who have joined us in partnership to offer their support and help launch this invaluable tool.

''Now it's down to the public to sign up for the alerts so we can send the message as widely as possible when a child goes missing.''

Jo Youle, chief executive of the charity Missing People, said ''Every minute after their disappearance is crucial to bringing a child home safely. Child Rescue Alert will now mean the public and companies can help - and hopefully save these children's lives.''