The strike by Oxford postal workers could expand to other areas of the country unless staff vote to return to work.

Crunch talks to resolve the dispute, now in its third week, were due to be held today with the national deputy general secretary of the Communication Workers Union, Dave Ward, meeting both management and staff.

But unless a deal is struck at a mass rally at the Cowley Workers Social Club in Between Towns Road, CWU bosses feel other parts of the country could join the dispute and moves may be made to make the wildcat dispute official.

National CWU spokesman Chris Proctor said: "Either the meetings make some progress or the strike will expand."

The strike was triggered by claims that a small group of workers carried out a campaign of abuse, intimidation and harassment against fellow colleagues and their families in a bid to rack up premium overtime rates.

Local union leaders say they are not optimistic staff will vote for a return to work.

CWU representative Bob Cullen said: "Talks are carrying on at national level, but we haven't spoken to local management for the past 10 days.

"The staff are desperate for cash. But at every meeting they have voted unanimously to stay out. This is not a normal strike."

Last week, management offered to disband the group, but said the strikers would be penalised with an overtime ban. The offer was rejected.

The number of workers taking action has since swelled to 480 with both the Headington delivery office and Royal Mail House in Becket Street joining staff on the picket line at the Oxford mail centre in Cowley.

Part of the conciliation process will involve management today introducing an independent counselling service for workers who want to air their grievances.

Royal Mail spokesman Richard Hall said: "There have been talks and things seem to be more positive.

"The counselling service will enable employees to raise any concerns they have but who may not be comfortable with the internal mechanisms."