Almost 1.4 million working days were lost through industrial disputes last year, the highest total since 1990, a new study has revealed.
The figure was boosted by the one-day stoppage by public sector workers last November in the bitter row over the Government's controversial pension reforms.
The Office for National Statistics said there were 149 separate stoppages in 2011, with almost twice as many in the public sector than in private firms.
In total, 1,389,700 working days were lost last year, over a million more than in 2010.
More than 1.5 million workers were involved in labour disputes last year, almost 12 times the number in 2010, said the report.
There has been a decline in the number of strikes over the past decade, although large-scale stoppages are becoming more common, the data showed.
Most disputes last year involved pay, although rows over jobs also sparked strikes.
Just over half of the strikes last year lasted a day, including the huge walkout by public sector workers.
More than 110,000 days were lost through disputes in private firms last year, the highest since 2004.
Almost 1,000 ballots for strikes were held in 2011, the highest number since 2006, with most returning majorities in favour.