Drunken Oxford students may be deliberately trying to get arrested for vandalism in a new kind of bizarre initiation, says the city's police chief.

Four students were arrested in two incidents on Thursday and Superintendent Jim Trotman, the commander of the city's police, said he believed freshers were now trying to get on-the-spot fines as some kind of "badge of honour".

The £80 fines, known as fixed penalty notices, were introduced two years ago for damage costing less than £300 to repair as a way of cutting red tape and keeping police officers on the streets, rather than filling in paperwork.

But Mr Trotman said last week's incidents indicated students may be deliberately trying to get caught to "earn" one of the penalties, partly because the fines do not go on criminal records.

However, Mr Trotman warned students that police would not let any craze develop and would issue cautions or file charges if necessary - which would appear in criminal records.

Early on Thursday, three Oxford Brookes University students were caught damaging cars in Cheney Lane, next to the Headington campus.

They had been drinking, said Mr Trotman, and spent a night in the cells at St Aldate's police station before being cautioned for criminal damage.

The same night, an Oxford University student was arrested after a till was damaged at one of the bars in the Park End Club. He was released on police bail.

Vandalism is one of the key crime problems in the city. Offences included under this heading include damage to vehicles, homes, business, and some racially and religiously aggravated incidents of damage and arson.

Mr Trotman said: "We suspect there's some kind of prank or initiation ceremony which may involve getting arrested for a minor crime or stupid stunt and getting a fixed penalty notice for disorder.

"The message is quite simple - don't do it. Students may not be aware of our crackdown on vandalism under Operation Rebound.

"While a fixed penalty notice doesn't carry a criminal record, we have cautions, charges or the possibility of using other antisocial behaviour powers to deal with them, so this mindless drunken behaviour can blight their future.

"We're going to take it up with the relevant universities."

Mr Trotman said evidence coming into the police suggested there was an ambition by the students to get caught.

He said he could not reveal the nature of that evidence.

The police campaign in Oxfordshire to combat vandalism has coincided with a period which has seen no rise in reports of criminal damage since April, compared with rises of between six and 12 per cent elsewhere in the Thames Valley.