Oxford's postal workers were today, Wednesday, March 31, back on the picket line after launching another wildcat strike amid allegations of bullying.

Striking postal workers on the picket line outside the Cowley sorting office

Staff at the Oxford mail centre in Cowley walked out after a meeting last night with union leaders furious at managers for not tackling what they claim is a campaign of harassment and bullying by one group against fellow workers.

Only 86 workers - half of those booked on to the late shift - reported for work yesterday. Thirty per cent of those due on the night shift turned up. This morning's shift saw only 25 per cent of workers on duty.

Communication Workers Union representative Bob Cullen said threats had been made against certain members of staff, with gangs turning up at their homes and even their children's schools.

Mr Cullen added the group was determined to rack up premium overtime rates at the expense of other staff.

Last Thursday, 39 workers walked out for 45 minutes after clashing with members of the group, which led to them having their overtime withdrawn for seven days.

Management refused to back down on their decision, which led to the mass walkout and today's unofficial strike. But they have launched an investigation into the allegations. Mr Cullen said: "They have told the staff who took action last week that they can't have overtime, but these thugs are doing 60 hours a week.

"These people are visiting workers' homes, their children in schools and threatening to beat people up.

"The victims are being victimised while the others get away with it. Management have totally abandoned their duty of care."

Yesterday, the Royal Mail said it was concerned by the unrest and admitted there have been "heightened tensions" in the office.

An independent company would be investigating by the end of the week.

The Royal Mail added: "Any person not following the high standards of behaviour we expect from Royal Mail employees will face the full weight of the conduct code agreed by both parties."

Royal Mail spokesman Jane Beese added the workers who staged the earlier walkout had been disciplined for taking unofficial action.

She said: "The reason we are stopping overtime payments to these people is to show them we are not going to accept that kind of behaviour."

Last year, a series of wildcat disputes by postal workers caused widespread disruption to postal deliveries across the county.