Downing Street has urged train managers who have announced strikes over Christmas to “rethink their position”.
On Tuesday, it was announced that train manager members of the Rail, Maritime and Transport union (RMT) at Avanti West Coast would strike over rest day working.
They are due to walk out on December 22, 23 and 29.
The Prime Minister’s official spokesman said on Wednesday: “I think the public will be rightly disappointed in that action.
“The last thing that people want to see over the Christmas period is disruption to their trains.
“We obviously urge them to rethink their position.”
It is understood that Avanti services will be extremely limited on the days of the strikes and a revised timetable will be issued from December 14.
Customers who have tickets for December 22 and 23 will be able to use them on alternative services between December 16 and December 24, while those with tickets for December 29 will be able to use them on alternative services between December 28 and January 3.
RMT general secretary Mick Lynch said on Tuesday: “Avanti West Coast’s proposals have been decisively rejected by our train managers, sending a clear message to management that the current arrangements are unacceptable.
“Train managers are being treated unfairly compared to senior managers, who receive significant payments for covering these roles.
“Our members have had enough, and this strike action demonstrates their determination to win a fair deal.”