Thousands of train drivers are to take action from Monday in a protest over safety levels, a union has said.

The action by up to 5,000 drivers could disrupt train services between London and Glasgow, Manchester, Crewe and South Wales, Aslef said.

Union members will refuse to drive trains in areas covered by a contentious communications system.

The union warned the action would cause "utter chaos" until the dispute was resolved to its satisfaction.

The announcement came after talks, continuing for years, between Aslef and Network Rail broke down.

The talks centred on the ability of drivers to alert other train drivers and signal operators to an accident or other problem on the track.

Aslef said the Interim Voice Radio System (IVRS), introduced two years ago as a trial, had failed on a number of occasions.

Acting general secretary Keith Norman said: "We will not be party to putting lives at risk.

"I hope the public will not only understand, but support, action aimed at saving the lives of our members and the public."