A BUS hell ride in which two passengers were stabbed has led to calls for all of the vehicles to carry security cameras.

Violence erupted in front of about 20 passengers about 7.35pm on Saturday after a man and woman approached two men sitting at the back of a Ventura bus travelling along Capon St, near Chadstone Shopping Centre.

A Chadstone man, 31, was stabbed in the face and neck and a 22-year-old was stabbed in the face.

The man and woman then ordered the bus driver to stop and let them off.

The Ventura Bus Lines vehicle did not have security cameras.

Over the past few weeks drunken youths on Dandenong buses have slashed seats and destroyed or stolen fittings.

The incidents prompted US Bus Lines to install closed-circuit TV cameras on two buses on problem routes.

Plainclothes police are also patrolling the services.

Bus Association of Victoria spokesman Russell Coffey said crime on buses was generally rare, but operators were seeing more of it.

"It's unusual. Normally we don't have these sorts of events but it would seem there's been an increase," Mr Coffey said.

"I think it's a reflection of social issues, but we're very serious about maintaining services as a safe environment."

About half of Melbourne's bus fleet had security cameras, Mr Coffey said, and they were being phased in on the remainder. But an immediate rollout would need state government support.

Public Transport Users Association president Daniel Bowen said CCTV on all buses would deter crime.

"You'd hope a plan to introduce CCTV, along with wheelchair access, airconditioning -- all the things that the bus link needs - is hopefully not too far off," Mr Bowen said.

Police hunting the Chadstone attackers are asking anyone who may be able to identify them, or who saw them fleeing in Middle Rd, to come forward.

The man was described as Caucasian, in his late teens to early 20s, about 170cm tall with short brown hair. He was wearing a dark, hooded jumper.

The woman, also Caucasian, was also in her late teens to early 20s and was wearing a light, hooded jumper.

Anybody with information is asked to contact Crime Stoppers on 1800 333 000.