NICOLA Sturgeon has lent her support to an online campaign which aims to help locate missing children.

The First Minister said she could vividly remember the disappearance of Sandy Davidson, a four-year-old who went missing in her hometown of Irvine when she was six.

The charity Missing People yesterday tweeted details of a missing person every half an hour, and encouraged Twitter users to share the posts in a bid to track down people who had disappeared, on International Missing Children's Day.

Ms Sturgeon shared details of Mr Davidson's disappearance and encouraged her 220,000 followers to do the same in an effort "to help find out what happened to him."

Age progression techniques have been used to predict how missing people such as Mr Davidson, who would now be in his 40s, would look now. He vanished from his gran's garden in 1976, leading to a huge police operation to find him, but the case remains a mystery.

The campaign, which used the hashtag #TheBigTweet, was backed by Madeleine McCann's mother Kate, who said the campaign "harnesses social media for good".

Celebrities getting behind the drive included Stephen Fry, Simon Cowell and J.K Rowling. X Factor supremo Mr Cowell tweeted: "It's that time of year again - @missingpeople's #TheBigTweet. Hopefully we can reunite more missing children with their families this year."

Mr Fry, the comedian, actor and host of quiz show QI wrote: "Is #TheBigTweet trending now? Families of @missingpeople deserve it to be. Still quite a few hours to go. Let's share #TheBigTweet people!"

Around 140,000 children go missing in the UK every year, the charity estimated and patron Mr Fry urged users to help "reunite families going through the worst experience imaginable". Last year, the initiative helped track down two missing people.

Meanwhile, Harry Potter author JK Rowling said: "Please RT these pictures of missing young people - you could be the one whose RT makes the difference! @missingpeople #TheBigTweet."