Liberal Democrat MP for Richmond Park Sarah Olney has written to Grant Shapps, saying he’s “sitting on his hands” to prevent volunteers attending it.
She says it’s a “new low” for the Tories.
A DfT spokesperson says it’s “completely untrue” and they’re working with the rail industry to mitigate disruption.
Members of the RMT Union are to walk out for three days over concerns about pay and redundancies.