More than one in five workers is tuning out of the workplace by listening to MP3 players at their desks, a study has found.

Some 22 per cent of employees use their iPod or other digital music player for up to three hours a day in the office, according to the survey. And 30 per cent of British firms have banned the devices.

Listening to music and podcasts has become another way for staff to shut out colleagues after open plan offices replaced partially enclosed desk cubicles, according to the research.

Of the 120 companies polled by workplace interior experts Woods Bagot between September and October, banking and legal firms were the least iPod-friendly, while the marketing and media sector was most tolerant of MP3 players.

The survey also found using the devices at work was driving a wedge between the younger "iPod generation" of staff and their older colleagues.

Simon Pole, of Woods Bagot, said: "By wearing the highly-visible white headphones, employees are sending a signal to colleagues that they don’t want to be bothered."

But a workplace communication expert warned firms that blanket bans on MP3 players was not the answer.

Cary Cooper, professor of organisational psychology and health at Lancaster University, said: "It’s crucial to give workers autonomy and bans of any sort can alienate them.

"Bosses shouldn’t care about how employees accomplish their objectives as long as the job gets done.

"Bans are more likely to isolate workers. Encouraging a culture of interaction is the only way to get more workers tuned into teamwork and not their iPod."

But the Confederation of British Industry said iPod use in the office could cost companies millions of pounds a year.

Spokesman Alan Mitchell said: "If staff spend time listening to music instead of working, that will reduce their productivity and so firms are quite right to ban MP3 players.