A group of children were spotted trespassing on tracks close to Stoke Mandeville railway station yesterday, forcing trains to slow through the area.
The driver of an Aylesbury to London service reported the incident to British Transport Police at 11.10am.
Officers searched the area but no one was found.
Police said they typically see an increase in such incidents during the school holidays and warned against such ‘mindless behaviour’.
A transport police spokeswoman said: “We are hoping that by targeting hot spot areas and highlighting the dangers of trespassing in an inherently dangerous environment, that we will deter the majority of youngsters from playing or hanging around on the region’s railway.
“We are also asking parents and adults to take responsibility and emphasise the dangers to your children, and if you live near the railway, ask yourself if you know where your children are playing.
“This is not about stopping children having fun, it is about keeping them safe from harm.
“We are working closely with colleagues from Thames Valley Police and Network Rail to crack down on this mindless behaviour before it’s too late.”