Madeleine McCann: Young children who have been missing for more than a decade

Police have begun searching a Portuguese reservoir as part of the 16-year-long investigation into the disappearance of Madeleine McCann.

The three-year-old went missing from the Algarve resort of Praia da Luz in May 2007, and her disappearance remains one of the most high-profile unsolved missing children's cases.

Madeleine's parents, Kate and Gerry McCann, have never given up looking for their daughter, writing at the beginning of May: "Today marks the 16th anniversary of Madeleine’s abduction. Still missing... still very much missed.

"The police investigation continues, and we await a breakthrough. Thank you to everyone for your support- it really helps."

Missing People estimates that around 70,000 children go missing every year - with more than 215,000 incidents reported each year as some children go missing more than once.

And, according to the UK Missing Persons Unit, there are 1,514 children in the UK recorded as "long-term missing", meaning that they have been missing for more than 28 days.

However, a smaller number of children have been missing for more than a decade - with investigations into their disappearances often ongoing.

Daniel Entwistle

Daniel was last seen in May 2003, when he was aged 7. The youngster went missing from Great Yarmouth in Norfolk, and was seen on `CCTV at Blencowes, a local convenience store, at around 5pm and near to the river at Trinity Quay with a group of other boys at around 3.30pm on the day he disappeared - 3 May 2003, a bank holiday weekend.

Police found his little red BMX bike close to the river and used sonar in a search of the riverbed, but did not discover any evidence of Daniel's disappearance. Daniel is described by police as being "3' 2" tall, of thin build with light brown cropped short hair. He had a pale complexion and a strong Northern accent".

Contact Tel: 01953 423819

Email: unsolvedcasereviews@norfolk.police.uk

Alternatively you can contact Crimestoppers anonymously on 0800 555 111

Ames Glover

Ames was just five months old when he disappeared from Southall in London. He was last seen in the backseat of his father Paul Glover's car in 1990. He left Ames in the car while he went to an ATM and a takeaway restaurant and when he returned, the baby had gone.

Despite police interviewing more than 20,000 people in connection with the disappearance, the baby was never found and his mother said she does not know if she believes her baby is still alive.

"Sometimes I think if he is alive he would have been found by now," Shanika Ondaatjie said in an interview with the BBC.

"But other times I think maybe whoever did it obviously concealed it so well they managed to get away with it."

Holly Bringan

Two-year-old Holly went missing in 2009. The youngster was reported missing on 22 October that year by her father after she and her mother Salena Dingwall disappeared from Irvine.

Police suggested at the time that Dingwall, who had previously worked for the police, may have set up a new life for herself and her daughter - and more than a decade after they went missing, police have no leads on the whereabouts of the pair.

If you have any information on the whereabouts of Holly and Salena call Police Scotland on 101.

Aamina Khan

Seven-year-old Aamina was last seen in the UK in 2011 and went missing from Croyden along with her mother, who did not have primary custody of her at the time.

Aamina is believed to have been taken to Pakistan by her mother, during a custody battle with Aamina's father.

He told The Mirror of his daughter: "She loved the parties, going disco and parties with her friends and going to the theatre."

If you have any information about Aamina's whereabouts, contact Missing People on 116000 or Met Police on 101.

Ben Needham

Toddler Ben vanished while on holiday with his family in Kos, Greece in 1991. The two-year-old was last seen at the family's holiday home on the Greek Island, where he was being looked after by his grandparents while his mother was at work.

Although the child was thought to have been kidnapped, and around 300 sightings of him were reported as part of the lengthy police investigation into his disappearance, it was later suggested that he may have died in an accident near the house.

Lead investigator Detective Inspector Jon Cousins told The Sun: "My team and I know that machinery, including a large digger, was used to clear an area of land on 24 July 1991, behind the farmhouse that was being renovated by the Needhams.

“It is my professional belief that Ben Needham died as a result of an accident near the farmhouse in Iraklis where he was last seen playing."

However, no body was ever recovered and Ben's mother has never given up hope that he will be found.

Mary Boyle

Ireland's longest missing child Mary Boyle was last seen in 1977 by her uncle, who said the then-six-year-old followed him across a field before he told her to turn back because it was waterlogged.

Almost 46 years after she disappeared, police have not managed to find any evidence about what happened to Mary or any clues as to her whereabouts.

Her twin sister Ann said she believed Mary was killed when she was six years old.

"I believe that Mary had a secret. And, because Mary was fiesty, Mary would have told," Ann Doherty said in a documentary about her sister's disappearance, Mary Boyle: The Untold Story.

"So I believe Mary had to be killed, to stop her from telling," she added, explaining she believed her sister had been assaulted by someone known to the family.