Image copyright EPA Image caption The aim is to reduce reliance on rest-day working, the rail operator said

A strike by conductors on the Southern rail network will still go ahead next week after the RMT was barred from ongoing talks, the union has said.

On Tuesday, the train drivers' union Aslef suspended three days of strikes next week for the talks to take place.

The RMT was due to strike next Monday and has said this will still go ahead.

RMT chief Mick Cash said the union wanted access to the same talks as Aslef. Southern said it was happy to have formal talks with the RMT.

"RMT demands again today that this union be given access to exactly the same talks process in our Southern rail disputes as has been brokered for our sister union by the TUC," Mr Cash said.

"We would remind all parties that not only is RMT a recognised drivers' union on Southern, but that it is also our guards members who have made huge personal sacrifices in the long fight for passenger safety."

He said the notion that a deal could be done that "leaves those Southern guards out in the cold" was ludicrous.

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Image copyright Getty Images Image caption The company has been hit by strikes since last April

A spokesman for Southern said: "The talks that are now taking place under the auspices of the TUC are as a result of a suggestion by Aslef, which we welcomed and accepted in order to find a way to end their drivers' dispute.

"As we have stated, we are happy to have formal talks with the RMT too when they're ready to do so, and lines of communication with them are open."

He said in the meantime, the company asked the RMT to follow Aslef's lead and suspend Monday's action.

Aslef went into talks with Southern on Wednesday at the TUC. The discussions are still in progress.

The RMT, which represents conductors and 12 drivers, has been involved in industrial action since last April.

The union's 12 driver members still plan to take action on 24, 25 and 27 January even though Aslef drivers have suspended their strikes on those days.

Southern issued guidance which said the RMT had 12 driver members out of 1,000 who worked on the network.

The company has said it will be able to run more than 70% of its trains during Monday's RMT strike.