POLICE have admitted they are looking at a potentially 'tragic situation' after divers failed to find any sign of a missing teenager in a swollen river.

Thomas Brown, 17, disappeared while out with friends in Methil, Fife on Friday and the search has centred on the River Leven.

A major police search operation is underway in the Levenmouth area, with friends of the teenager helping officers and family members look.

A helicopter has already scanned the mouth of the river and the coastline where it flows into the Firth of Forth.

Divers from Police Scotland's underwater search unit joined the hunt.

Chief Inspector Graeme Kinmond, in charge of the operation, said the unemployed teenager, from Springfield, near Cupar, vanished while out with friends on Friday night in an area known as "The Dam" at Methil, by the banks of the in-spate River Leven.

He said: "It is very poorly lit at the Dam, and he was with a number of friends. He may have consumed alcohol.

"It was extremely dark and he was walking in conversation with his friends."

When they reached an area where there was better lighting, they realised he was no longer with them, but they simply thought he had taken another route home.

"But we are now potentially looking at a very tragic situation".

His sister-in-law Janet Brown said the youngster's family were assisting the police.

She described him as a quiet, normal 17-year-old, adding: "We are worried sick about him.

"His whole family was out searching today and he could be anywhere, because he's got friends all over.

"Thomas's family don't know very much yet.

We are all just searching and are very worried."

By the time Thomas was reported missing at around 2pm on Saturday, relatives had not heard from him for a number of hours.

The teenager, who is from near Cupar, had been with a group of young people in the Steelworks Brae area of Methil.

When he was last seen, he was wearing a grey hoodie with a blue hood, a black T-shirt with an orange logo and grey track suit trousers with denim pockets.

He is 5ft 5in and slim-built.He has blue eyes and his hair is shaved at the sides, but is longer on top. His family said that it was out of character for Thomas not to keep in touch, as he usually texts and phones regularly.

Inspector Andrew Sneddon, who is coordinating the search, said that police were becoming increasingly concerned for the youngster.

He said: "The area in which he was last seen is well used by dog walkers and I would urge them to let us know if they see anything which may help us trace Thomas."

Anyone with information should call 101, or Crimestoppers on 0800 555 111.