NEWPORT is the top UK troublespot for youngsters trespassing on the railway or attacking trains and lines over the last five years, a top transport policeman says.

And Inspector Ian MacDonald of British Transport Police says the problem reaches its peak at this time of year - the school holidays.

He says there was a worrying total of 64 malicious acts on rail lines in Newport between 2003-2004 - one incident a week.

These include throwing rocks at trains and placing objects on the line. "Children do not take on board the consequences, which can be very grave indeed," he said.

In a recent incident, he said, a group of youngsters were spotted putting rocks on the main line in Somerton.

"The trains go through to London at 80mph and it takes about a mile for one to stop at that speed," he said.

"Obviously they are risking their lives as well as the lives of passengers if they cause a derailment.

"On average, Newport is the highest ranked problem area in the UK over the last five years."

In the case of the Somerton attack, the culprits escaped, but police say they will crackdown and prosecute the trespassers they catch.

A joint initiative by Network Rail and British Transport Police is being stepped up during the summer months.

Operation Hawk, covering the South Wales area, involves the use of a police helicopter, which is being scrambled from Cardiff Heliport on a regular basis, in a bid to intercept intruders.

The minimum punishment is a £1,000 fine for trespassing, but there is the possibility of life imprisonment if intent to cause a train crash is proved.

Nancy Garcia, Network Rail's route crime manager for South Wales, said: "With long days and light evenings, it's easy to understand why children want to play outside - but it's hard to understand why some risk their lives playing on dangerous railway tracks.

"We implore parents and guardians to make sure their children understand the dangers of playing on the tracks. We don't want any child to die as a result of playing on the railway this summer."