More days of work were lost to industrial action in the UK last year than at any time since 1990, official figures have confirmed.

Data from the Office for National Statistics revealed that almost 1.4 million working days were lost in 2011, up from 365,000 in 2010. There were 184 individual stoppages and around 1.5 million workers took part in some form of industrial action.

Two days of co-ordinated public sector strikes over pensions accounted for the lion’s share of the disruption, although private sector action had also doubled from the previous year and stood at its highest level since 2004.

Law firm Freshfields Bruckhaus Deringer, which carried out a detailed analysis of the figures, said the statistics would reignite the political debate over reforming balloting laws. Some leading Conservative politicians, including London Mayor Boris Johnson, have spoken out in favour of a minimum turnout that should be required for industrial action to take place, a policy also backed by the CBI.

“With a further wave of public sector strikes planned for March, the government may face fresh calls to change the law by making it more difficult for employees and trade unions to organise and participate in industrial action. Nick Squire, Freshfields' employment partner.

“A very simple question lies at the heart of industrial action legislation – where to draw the balance between an employee’s right to withdraw his labour and the freedom of a company to run its business? Even a very subtle shift in the scales can have a significant impact, making it either much easier or harder to go on strike.”

Squire said that there had been a steady decline in strike action since legislation enacted under the Thatcher government in the 1980s, but that there was a risk that returning to similarly tough approach to the unions might be counter-productive.

“While legislation which favours employers has reduced industrial action, during a time of widespread cuts, it is in the government’s interests to carefully manage the delicate relationship between enterprise, employees and trade unions to minimise the potential of increased strike action,” said Squire.