Cabinet minister Francis Maude was left red-faced on Thursday after scores of civil servants walked out in protest over his visit to their offices.
The Public and Commercial Service (PCS) union said around 200 of its members at HM Revenue and Customs offices in Coventry took part in the 15-minute walkout
The protest followed previous comments by the minister that workers could hold 15-minute stoppages instead of full days of strike action.
200 civil servants walked out when Francis Maude walked in
The PCS is campaigning against plans to review terms and conditions in the civil service at a time when jobs, pay and pensions are being cut.
Andrew Lloyd, the union's Midlands regional secretary, said: "These latest proposals feel like further punishment to civil servants just for being public sector workers, and of course is an attempt to divert attention from the fact that the Government's cuts have not made matters better, but worse."
A Cabinet Office spokesman said: "We would like to thank the hard working majority of civil servants who have turned up to work today to deliver essential services. We are reforming the civil service so that it is faster, more unified, focused on outcomes not process and ultimately more enjoyable to work for."