The UK is facing a productivity “puzzle”, with the country lagging behind its economic rivals, according to the head of conciliation service Acas.

Sir Brendan Barber said UK labour productivity in terms of GDP (gross domestic product – a measure of economic output) per hour worked in 2007 was 9% below the average for the G7 group of leading economies, which includes Canada, France, Germany, Italy, Japan and the United States as well as the UK.

He said in a New Year message that, by 2013, the equivalent figure had grown to 19%, representing the biggest gap between the UK and its nearest rivals since 1992.

Sir Brendan said: “Previous solutions debated have ranged from improved education and skills levels to easier access to finance and better corporate governance. These may all have relevance but we are still left with a productivity puzzle.

“What is often overlooked which I feel will have a big role to play is the workplace itself, through better workplace management and employment relations.

“The workplace so often gets overlooked when the focus is on institutions and policy. One striking finding from the latest survey in the Workplace Employment Relations series was that businesses that had established good relations with their workers were less likely to have been damaged by the recession.

“At Acas we believe that prevention is always better than the cure and it is clear that good relations at work is key to building a solid recovery.

“All these issues will no doubt feature strongly in the 2015 General Election debate.”

Sir Brendan, who retired as general secretary of the TUC at the end of 2012 and was appointment chair of Acas earlier this year, predicted more days of co-ordinated industrial action in the public sector in 2015 over pay.

He added: “With the economy now beginning to show distinct signs of recovery, although unevenly across the country, workers are expecting this good news to be reflected in their pay packets.

“This is certainly happening in some parts of the private sector but pay has not risen in the same way within the public sector, which is inevitably leading to employment relations tensions.”