A YORK head teacher today begged parents to keep track of their children over the Easter holidays - and not let them play on potentially lethal railway lines.

The comments by Mark Barnett, head teacher at Westfield Junior School, came as British Transport Police and rail firm Railtrack today joined forces for a hard-hitting poster and video campaign showing the last moments of a child's life - and aimed at reducing the toll of deaths and serious injuries on lines.

Last year 122 people, many of them children, were killed and another 149 seriously injured after trespassing on tracks.

Tragedies have resulted from:

l Youngsters playing dare and "chicken"

l Children playing near to lines and slipping or stumbling onto them

l Children and adults crossing railway lines as a "short cut"

l Young vandals placing obstacles such as sleepers and even empty shopping trolleys on tracks.

Today's Track Off poster and video campaign - designed to shock parents and children into taking notice - is backed by "eye in the sky" helicopter patrols across Yorkshire and the North East to catch trespassers in action.

Welcoming the initiative, Mr Barnett, chairman of York Safer Schools, said youngsters were naturally drawn to dangerous areas such as railway lines. But trains travelled at such speed they would not realise they were in danger before it was too late, he said.

A nine-year-old boy was killed in 1994 and a 12-year-old in 1995 after being hit by trains, both near Goole.

And in 1992 a York teenager was lucky to survive after falling on to a 25,000 volt overhead power line on the East Coast main line at Dringhouses - and landing just inches from tracks as a train sped by.

Mr Barnett said: "Railway lines are extremely dangerous places.

"Parents need to know what their children are doing at all times. They have to be responsible. Most are very good, but there is a minority who don't know what their children are up to. The bottom line is, every head wants all their children back in school after Easter."

Railway vandals were also being targeted from today.

Chief Insp Keith Groves, head of operations for the transport police in the North-East, said teams of officers would be out over the Easter holidays patrolling railway lines, including in York.

Anybody found committing acts of vandalism would feel the full weight of the law, he said.

Last week in South Yorkshire a metal pole was placed on a railway line which pierced the underneath of a passenger carriage. And in West Yorkshire, projectiles were dropped on to passing trains at a tunnel. Nobody was hurt, but both incidents are being investigated.

Chief Insp Groves said anybody convicted of endangering life on the railways could face imprisonment.

"We have far too many deaths on the railways," he said.

"Anybody caught doing this kind of thing will be prosecuted."

l Anyone who sees children playing around railway lines or leaving dangerous items on the track should call British Transport Police on freephone 0800 405040.