Children as young as four are risking their lives by playing on railway lines at danger spots across Bradford, a British Transport Police inspector warned today.

Youngsters are cheating death while trespassing on the lines and in some cases leaving obstacles which have been struck by trains.

More than 130 incidents have already been reported in the Bradford district alone this year - and that figure is expected to rise further during the rest of the summer holiday.

A train travelling from Bradford Interchange to Leeds suffered damage and was almost derailed after striking debris which had been left on the track at Laisterdyke earlier this year.

And two trains came within inches of a serious accident when four six-foot tall metal shelving units were thrown in to the path of trains on the Leeds-Bradford line close to the Dick Lane road bridge last month.

Six Bradford youths have been handed final warnings after being found guilty of leaving a shopping trolley, bollards and other debris on the track during the first incident on May 15.

But it is feared there could be a repeat of the incidents - and the British Transport Police have joined forces with regional operator Arriva Trains Northern to try to combat the problem.

Officers are now being employed to patrol key problem areas to track down those responsible.

Today Inspector Cameron Young, of British Transport Police in Leeds, said there were a number of hot spots in the Bradford district.

As well as the two incidents when trains have collided with obstacles on the line, children have been spotted trespassing on the tracks and throwing stones and other objects at moving trains.

"The summer time is the peak of the year for problems such as this because of the light evenings and the long holidays when children can get bored and look for things to do," said Insp Cameron.

He said the worst areas were at Bowling, Laisterdyke and on the stretches leaving the Bradford Interchange and Forster Square stations. There have also been reports of incidents in Bingley, Saltaire, Pudsey, Shipley, and Brighouse.

Insp Cameron said a crackdown in the Bowling area had successfully cut the number of offences there in the past 12 months - but appealed to parents to help.

"We have cases of children as young as four or five taking part," he added.

Anyone with information about children trespassing on tracks is asked to contact the British Transport Police hotline on 0800 405040.