A rail company has rejected calls for greater security on trains, saying it is not responsible for the behaviour of trouble-making passengers.

Vanessa Clifton-Lawrence, 30, made the plea after a gang of teenagers verbally abused passengers as she returned from London to Brighton.

She says rail users need greater protection from yobs and train companies should step up security but South Central says it is not its problem.

Mrs Clifton-Lawrence spoke out after five boys and three girls, aged 11 to 15, spat at a woman and vandalised a toilet on the South Central train.

She said: "I was very frightened. They were running up and down the train and intimidating people. They became confrontational if anyone looked at them.

"No one knew how to deal with the situation or dared to get involved."

Mrs Clifton-Lawrence, who was on the 10.38pm Brighton Express, called the police from her mobile phone but no one from the emergency services arrived. There were no guards on the train.

She said: "I became very nervous as soon as I had made the call to the police. I was trapped in the train and felt I had drawn attention to myself.

"I've seen several incidents like this and I've just had enough. Passengers are putting themselves at risk by travelling on late-night trains. You never know if someone is about to pull a knife.

"These were not just young kids messing about, they were very aggressive."

Mrs Clifton-Lawrence, who lives in Brighton but commutes to London for work, said police or guards were needed.

She said: "When you think of the service we get and how much travelling costs it's outrageous. People are paying more to put themselves at risk."

Sergeant Jack Ioannou, of British Transport Police, said: "We will investigate and will contact the woman involved.

"British Transport Police is working closely with the train companies to improve security.

"We are working very hard to reduce crime on the railways."

A South Central spokeswoman said the company did not put guards on the Brighton Express service.

She said: "It is not down to South Central to manage the behaviour of passengers. We run trains, we are not there to stop people behaving badly.

"If anyone feels concerned about the behaviour of other passengers they should pull the emergency cord.

"Safety is a priority at South Central. It is not up to the railway industry to try to change the behaviour of people."