Members of the train drivers' union ASLEF are to hold another week of industrial action at the start of December over their pay-claim, including a one-day strike on Greater Anglia.
All ASLEF members will refuse to work any overtime from Friday December 1 to Saturday December 9.
Members who are employed by Greater Anglia will hold a one-day strike on Tuesday, December 5.
A spokeswoman for Greater Anglia said the details of what services would be affected were still being assessed - but there was likely to be very widespread disruption on December 5.
She said: "On strike days we are only able to run about 10-12% of our services. On the other days there may be some disruption but there should be some services on all lines."
Details of changes would be published in advance - but anyone planning to travel by train during that week should check before they start their trip.
The ASLEF action was called as members of the RMT union are being balloted on a possible settlement to their dispute with the train companies which started 18 months ago.
Their industrial action is on hold pending the result of the ballot and there are hopes the latest offer will be accepted.
However, ASLEF general secretary Mick Whelan said his members were determined to hold out for a better deal.
He said: “We are determined to win this dispute and get a significant pay rise for train drivers who have not had an increase since 2019, while the cost of living, in that time, has soared.
“Our members have spoken and we know what they think. Every time they vote – and they have voted overwhelmingly – for strike action in pursuit of a proper pay rise it is a clear rejection of the offer that was made in April.”
A spokesperson for the Rail Delivery Group said: “This wholly unnecessary strike action called by the Aslef leadership will sadly disrupt customers and businesses ahead of the vital festive period, while further damaging the railway at a time when it is still getting an extra is £175 million a month in taxpayer cash.
“The fair and affordable offer made by industry, which would take average driver base salaries for a four-day week from £60,000 to nearly £65,000, remains on the table."
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