The Oxford depot was being used to sort the London backlog

Staff at the Headington mail centre have now joined up to 75 staff who walked out of the Cowley depot at about 2000 GMT on Tuesday.

The Cowley staff walked out after Royal Mail drafted in casual staff to sort the backlog of post from unofficial strikes in London.

The wildcat strikes follow action over the last 10 days in London over proposed changes to working practices. There is still widespread disruption to deliveries and collections.

They haven't asked us to get around a table and talk about what the issues are Brian Jeffries, of the CWU

It also comes just one month after workers in depots across Oxfordshire walked out in a series of strikes over the suspension of three of their colleagues.

Royal Mail denied anyone had been suspended, saying some members of staff had pay docked for refusing to carry out an instruction from a manager. The dispute was resolved.

Other delivery offices in Oxfordshire are working as normal on Thursday.

Brian Jeffries, from the Communication Workers Union, said: "They haven't yet asked us to come in and meet them.

"They haven't asked us to get around a table and talk about what the issues are - they have really just left us alone."

Michael Stockdale, Royal Mail general manager for Oxford, said: "Well let's just be real about this.

"I don't think the issue is about trust it's about customer service and I think it's about being professional.

"We want to move the relationship with the union forward and we want to have a sensible conversation with them and a sensible relationship with them that stops random illegal acts of industrial action happening in Oxfordshire."