TRANSPORT police are warning Bolton youngsters to stay away from railways as a spy in the sky plane targets the town's troublespots.

Police have launched Operation Skyhawk with Railtrack, where a plane will spot youths causing vandalism. It will be extended if it is a success.

Police said one area being targeted was the railway tunnel at Farnworth which has been plagued by trouble.

Four boys aged 13 and 14, and one girl aged 14, were spotted interfering with a signal and putting concrete on the track in Atherton on Wednesday. Chief Inspector Peter Holden said all five were taken to their homes nearby and would be interviewed this week.

"Although the signal appears to be undamaged and the amount of stones on the track would not have derailed a train, this is yet another example of foolish behaviour by youngsters.

"There could have been more serious consequences should their actions not have been curtailed by us. Our advice for all concerned is to stay away from the railways. It is not a playground."

Other areas targeted include Moses Gate, which Railtrack last year named as one of its top 20 troublespots in Greater Manchester.

Between July 2000 and July 2001, Bolton had five incidents of vandalism and seven of trespass, and Bromley Cross had two incidents of vandalism.

In Farnworth there were seven incidents of vandalism, including trains being struck by objects and objects being placed on the line causing possible de-railing. In Moses Gate there were eight incidents of vandalism and seven of trespass.

The pilot project is for three days but will be extended if it is a success.