Staff at the Department for Work and Pensions have been blocked from accessing Facebook during working hours it has been revealed.

According to the Press Association, the employees for the government department can still access micro-blogging site Twitter but only for work reasons. The admission came following a written Parliamentary question from East Dunbartonshire Lib Dem MP Jo Swinson.

"The department recognises social media is a valuable tool for engaging with jobseekers and partners. All staff have access to LinkedIn and Twitter for business use and the department actively uses social networking to communicate with customers," said employment minister Chris Grayling.

"Access to some internet sites from departmental computers is restricted or blocked. This includes Facebook."

However, Grayling admitted those whose jobs "involve use of social media" could still log on to Facebook. He did not reveal if staff activity on the site was monitored to ensure it was only being used for work purposes.

But he did not say how internet usage was monitored to ensure civil servants only used the sites for work purposes.

The news comes just days after research by security software firm Clearswift revealed nearly one in five (19 percent) of global firms are blocking access to social media sites such as Facebook and Twitter during work hours.