Madeleine McCann’s mother Kate has spoken of the “anguish” of life with a missing child ahead of International Missing Children’s Day.

McCann, 50, revealed she often feels isolated and still hopes that one day she will find find an answer that leads to Madeleine, who disappeared aged three on a family holiday in Portugal in May 2007.

The former GP said she has backed a Twitter campaign to raise awareness of all missing children. She said: “Having a missing child, you live in anguish and hope that one day you’ll find the answer that leads you to them.

“It feels isolating, and for families like mine with a missing child, knowing that people care and want to help is so important.

“The ‘Big Tweet for Missing Children’ creates a simple way, on an important day, to galvanise as many people as possible to help remember, and hopefully find, children who are missing.

“It is heartening to see social media being used for good and I encourage everyone to help. One tweet could find the answer.”

Maddie would now be 15-years-old.

The Big Tweet campaign is being led by charity Missing People, whose choir made the final of Britain’s Got Talent last year. Avid tweeters and big names are due to join a 24-hour tweetathon on Friday, International Missing Children’s Day.

Celebrities from the worlds of film, music, television and sport are due to take to the social network to show their support.

Missing People will tweet an appeal for a missing child every 30 minutes over 12 hours.

The charity aims to bring 180,000 missing children and adults back home each year.

[READ MORE: 3 parents reveal the devastating reality of a decade spent searching for a missing child]

Jo Youle, CEO of Missing People said: “A staggering 24 children go missing every hour, and that’s in the UK alone. On International Missing Children’s Day on 25 May, and in the year that Missing People marks its 25th anniversary, we implore the public to get behind the Big Tweet to really make this year count.”

Twitter said it was a “privilege” to host the campaign.

Dara Nasr, Managing Director at Twitter, said: “It’s heart-warming to watch communities support each other by sharing appeals for missing people, which is something we see regularly on Twitter. It’s a real privilege to host the Big Tweet and to offer our platform as a way of getting the faces of these vulnerable children into the public eye.”

The Big Tweet 2018 is also being supported by players of People’s Postcode Lottery, who have raised a combined total of over £5million for the charity since 2009.

Missing People runs a free, confidential and 24hr helpline, 116 000, which is supported by players of People’s Postcode Lottery. The helpline provides practical and emotional support to missing people and their families, and can also take anonymous sightings and information about missing people. People can also email 116000@missingpeople.org.uk – free, confidential, 24/7.