The state of Oxford's postal service was described as "pure and utter chaos" by one worker as striking postal staff vowed to continue their action through Easter and beyond.

Undelivered post at the Cowley sorting office

About 150 workers at the city's Cowley mail centre unanimously voted to continue their unofficial action until at least Wednesday. April 14, when they met at the Cowley Workers' Social Club on Thursday.

They are no closer to settling the dispute with management who, they say, have reneged on verbal agreements which could have seen them return to work.

Managers deny breaking any deal and say they are available for talks whenever the union wants.

The union claims that the massive backlog of undelivered mail will take at least three weeks to clear.

Communication Workers Union representative Steven Gill said: "The management are penalising us and it's causing a hell of a lot of disruption.

"The backlog will take about three weeks to clear even with skilled staff, but they'll have to bring in casuals who are not skilled to do the work, and it's just pure and utter chaos."

The strike centres on claims a small section of workers carried out a campaign of abuse, intimidation and harassment against colleagues and their families.

And while the striking workers say their action will last indefinitely, the group at the centre of the allegations is continuing to work as a team at the centre on overtime.

Area processing representative Bob Cullen claimed management had withdrawn a promise to remove these workers from the centre while an investigation into the allegations was carried out. Now he says, as a punishment for walking out, workers will have to endure punitive measures when they return, including a 14-day ban on overtime.

Mr Cullen said: "The management has withdrawn a concession made earlier to remove these alleged harassers from the building so people could feel safe at work. The staff felt it was not a safe environment and would no longer work there. We're further away from reaching an agreement than we were before, but we're always optimistic of making progress.

"Postal workers are certainly not highly paid, but it's no longer a question of money -- it's the principle. We are extremely sorry, but would you work under conditions where people are being bullied by thugs?"

Royal Mail driver Peter Boswell, 57, said: "I have never seen morale to be this bad. No one wants to be on strike, but this is not about money it's about the principle of the matter."

Royal Mail spokesman Richard Hall said: "Although it is not in the latest return-to-work agreement, the offer is still there to move the people at the centre of the allegations to other Royal Mail sites, without prejudice."

He added: "We want our people to come back to work. It's not doing our staff, business or customers any good. What we have got to do is restore a consistent and reliable service and a stable work environment.

"We are available for talks with the union whenever they want."

On Wednesday the Royal Mail took out a half page advertisement in the Oxford Mail to apologise to its customers for the inconvenience caused by the strike adding that customers deserved better.

The strike is the fifth unofficial dispute since September last year.