Train drivers union Aslef has announced two more days of strike action to coincide with the Tory party conference.
Aslef members at sixteen train companies would walk out on 30 September and 4 October, with an overtime ban on 29 September and for five days from 2 to 6 October.
The Conservative Party conference this year is being held in Manchester from 1 to 4 October.
Strikes by members have been occurring for eighteen months due to a dispute over pay and changes to working conditions.
An offer that incorporated working practice changes alongside pay rises of 4% for one year and 4% the next was rejected six months ago by union leaders.
Transport Secretary Mark Harper described the latest strikes as "cynical" and "politically motivated".
Mick Whelan, Aslef’s general secretary, said while the union regretted striking again, "the government, and the employers, have forced us into this position".