The RMT has called for an increase in policing on trains

Figures from the British Transport Police show there have been 42 attacks on train staff since 1 April 2005.

RMT official Brian Curtis said incidents included bricks being thrown through windows and gang fights spilling onto trains.

The union said it has met train operator Arriva to discuss violence against staff.

Fighting

Mr Curtis said assaults on rail staff were a "long standing" problem but that recent incidents have been "very, very severe".

"We've had a train pull into the station and people climbed on the roof of the train - trying to beat their way through to get at the guard and the driver.

"We've had one or two serious assaults - spitting at guards is a common thing these days.

He added: "There was a very severe incident in Barry as well when there was two separate gangs fighting, and that spilled onto the train - this is almost civil unrest."

Mr Curtis also called for a "dramatic increase" in policing on the railways and more monitored CCTV coverage of stations.

There was firework throwing on the train a few weeks' ago - I'm often a bit worried on here Passenger Brigitte Pimm

Employing security guards on trains to help keep order was not the same as having regular police who could make an arrest, he said.

And some passengers who use the Valleys rail line have claimed employing security guards has just increased problems.

Passenger Gareth Beady told BBC Radio Wales: "Since they put the security guards on the trains a lot of the kids are seeing that more of an opportunity to get a rise out of them.

"There was always rowdy kids before that, but it has increased at an exponential rate since the security guards came on board."

Another passenger who regularly uses the Treorchy line said she did not feel safe on the train.

Brigitte Pimm said: "There's quite a lot of yobbish behaviour and you often get teenagers getting on here with cans of lager and they often cause trouble.

"And there was firework throwing on the train a few weeks' ago - I'm often a bit worried on here."

Bricks and stones

Police said many of the offences on trains were related to drinking.

Some stations have removed benches on platforms to try and stop people gathering there.

Pc Derek Anderson, who works in plain clothes on the railways in the south Wales Valleys, said they were trying to crack down on incidents in the Rhondda.

"There's a lot of what we call train surfing, when they grab on the backs of trains as they go out," he said.

"They also open doors from the outside - which puts a train's brakes on - (throw) bricks and stones through windows of trains.

"People get off the train and they're harassed by 20 to 30 youths."

Councillor Cennard Davies told BBC Wales the police, community and train companies needed to work together to reduce the problems.

He said cleaning stations up would be the best start.