COPENHAGEN – Nearly one-third of Danes regularly log on to Facebook at work, mingling away the equivalent of about 1.5 billion euros in lost working hours each year, according to a poll published Tuesday.

The poll, conducted by the Dwarf and Userneeds institutes between February 2 and 8, showed that some 55,000 Facebook users spend more than 30 minutes of each work day logged on to the social networking site.

According to the Boersen financial daily that published the poll, the time spent on Facebook cost Danish society 10.8 billion kroner (1.5 billion euros, 2.0 billion dollars) a year in diminished productivity.

"We knew that this problem existed but we are surprised by the extent that this is impacting productivity and competitiveness," Charlotte Vester, the deputy director of the Danish Chamber of Commerce, told AFP.

"We really do not need to be world champions in using Facebook in the workplace," she said, adding it was up to employers to "set rules for using this network to prevent excesses that will damage work efficiency."

While some companies do encourage employees to use Facebook as a work tool, only 7.8 percent of the 2,545 public and private sector professionals questioned for Tuesday's poll said they used the network professionally.

The survey also showed that Danes with high levels of education were most likely to log on to Facebook at work.

Some 1.9 million Danes between the ages of 16 and 65, or around half of the Scandinavian country's population in that age group, have profiles on Facebook.