Railway workers are threatening to go on strike after the number of attacks on staff soared.

The Rail, Maritime and Transport Workers Union (RMT) said it is in formal dispute with Southern Railway claiming the operator is putting staff at risk by cutting back on security measures.

Operations staff, including ticket inspectors and guards, will be balloted in the next week and a full strike will happen before Christmas if members vote for a walkout.

Last year Southern decided not to renew its contract with security company Meteor, which guarded known trouble hotspots on the network.

Instead in April, Southern and British Transport Police (BTP) set up a team of Rail Neighbourhood Officers which work across the network.

The BTP said reported assaults on staff rose by 22% between April and September this year, compared to the same period in 2009.

A total of 49 staff assaults have been reported since April and the RMT said eight of those happened during the first weekend in August alone.

A Southern spokesman said the firm was "extremely surprised and disappointed" by the RMT's comments.

He said: "We regard the safety and security of our passengers and staff as our highest priority and we strongly refute the accusation that we have cut back on security measures and that there has been a cost cutting exercise of any kind."