Thousands of rail passengers face major delays to their journeys after train guards voted in favour of three one-day strikes.

The RMT union announced the industrial action, starting this Friday, after safety talks with rail operators broke down.

Train crews will walk out for 24 hours on Friday, next Monday and on April 17 as a protest against changes to the role of guards.

South Central, which runs services across Sussex, is one of ten UK rail operators whose crews will take part in the action.

Rail chiefs have insisted they will try to run as many peak-time services as possible to minimise disruption to journeys.

Some managers will be given special training to perform the duties of guards who refuse to clock on for their shifts on strike days.

However, South Central admitted coastal services across Sussex would be cut.

Talks between the RMT and operators failed to secure agreement on returning key elements of the guards' safety role to the railways' operational rulebook.

RMT general secretary Bob Crow said: "We allowed the operators a week's grace after they approached us for more talks.

"These train operators have already reneged on one agreement and they have now walked away from a second chance to settle the matter without industrial action.

"Eight companies have already signed up to restore the guard's proper safety role to the rulebook and there is no earthly reason why the others should not do so.

"We can only assume that they intend to diminish further the role of the guard and to extend driver-only operation and that is completely unacceptable.

"The fact that some operators intend to use hastily and inadequately trained managers to undertake guards' duties on strike days underlines our concern at their increasingly cavalier attitude towards safety."

Talks are set to resume tomorrow in an effort to reach a compromise.

A South Central spokeswoman said the firm would try to ensure services on the Brighton mainline and Gatwick Express route would run as normally as possible.

Some trains would be cancelled, however, though she said timetables would not become clear until later this week.

She said: "We will try to run certain peak-time trains on the east coast between Hastings and Eastbourne and London and on the west coast from the Arun Valley.

"The RMT has balloted its members and they have come out in favour of industrial action but we want to continue talks to try to prevent any strikes."

Thameslink is due to run its normal services as scheduled.