The walk-outs at the Carterton and Witney delivery centres began last week after the suspension of one employee and claims of bullying by another.

The Communication Workers Union, which did not back the action, said staff went back to work reluctantly after an agreement was reached with Royal Mail.

Procedures have been put in place to resolve problems at the two centres.

Twenty-three workers took part in the Carterton strike, which began on Thursday.

At Witney, 61 employees were involved in the action, which lasted from Friday until Tuesday.

Royal Mail said: "Everything will be done to get services back to normal as soon as possible and we hope to achieve this by the end of the week.

"We would like to apologise to all of our customers for the disruption caused by this unofficial dispute."