Bus drivers are facing daily violence and abuse but many attacks are not being reported, trade unions say.

They said police were not doing enough and dozens of incidents could be going unreported because drivers did not think they would be investigated.

The comments came as unions launched a survey of bus drivers in Brighton and Hove to gauge the scale of the problem.

GMB union organiser Gary Smith, said: "They are not convinced the incidents they suffer are being treated seriously, particularly by the police.

"There is really nasty verbal abuse and spitting occurring on a day-to-day basis.

"Drivers are really worried. I am sure dozens of incidents go unreported."

The survey, which is being supported by the Brighton and Hove Bus and Coach Company, would provide pointers to the scale of the problem but Mr Smith warned there were no quick-fix solutions.

There has been a spate of robberies and attacks on drivers and vehicles since the beginning of the year.

Recent incidents include a driver being spat at in Rottingdean, another punched in the face in Sutherland Road, Brighton, and a third being robbed at knifepoint in Moulsecoomb.

Mr Smith said: "Ourselves and the company are keen to see more action against these thugs.

"We will be putting pressure on the police to do something constructive about it.

"There has been a lot of rhetoric but I am not sure that has translated into conclusive action."

Undercover and uniformed police officers have begun riding on some buses because of the robberies and attacks.

Police said two juveniles had been arrested in connection with bus robberies since the launch of the operation.

Chief Inspector Peter Mills said police had discussed crime prevention measures with the bus company but it was up to managers whether the measures were implemented.

Bus company managing director Roger French said police had been very active in trying to stem the attacks and initiatives such as CCTV were being used to trace offenders.

He said: "We do encourage staff to always report. There is, I think, much more awareness now of the need to report incidents.

"Just one incident where a driver feels threatened is one incident too many. We must work to find ways to overcome this."