EXTRA police patrols have been put on at Hartshead Moor Service Station after concerns over men importuning for sex.
Motorists stopping at the M62 services near Brighouse have seen pairs of men going into toilet cubicles together during early evenings.
This has been happening for several weeks at toilets on both the east and westbound carriageways.
Police say nothing untoward has happened, but they want to stop the activity before problems do arise.
The toilets have been used as a meeting place for voyeurs in the past.
Sgt Andy Wilkinson, area sergeant for Brighouse and Elland, said: "Men appear to be coming from various places to these toilets.
"It seems to happen mostly in early evenings, when people are on their way home from work.
"We have a police officer based at Hartshead and she has been paying extra attention to the toilets."
Sgt Wilkinson said the problem was common at other service stations.
He added: "It's nothing new. It's just that attention has been drawn to it."
The problem of men gathering in the toilets was first spotted by the service station management.
A security guard was called to evict several casually dressed, professional- looking young men from the cubicles.
As well as extra police patrols, notices have been put up, warning people that the toilets are under surveillance.
Chris Taylor, general manager at Hartshead said: "We won't tolerate this behaviour."