Around 33,000 more civil servants in Britain, including those working for the tax office, have voted to stage a strike on March 15 in a dispute over pay, pensions and job security, the Public and Commercial Services (PCS) union said on Tuesday.
They will join 100,000 civil servants across other government departments who were already scheduled to strike on the same day.
"Unless ministers put more money on the table, our strikes will continue to escalate, beginning on March 15," PCS General Secretary Mark Serwotka said in a statement.
