An unofficial postal strike in Oxfordshire is set to continue after some workers voted unanimously against returning to work at a meeting.
Staff have set up a picket line outside the Oxford sorting office
Services were disrupted across the county after at least 300 staff walked out of the Royal Mail sorting office in Garsington Road, Cowley, on Monday.
They are protesting against the suspension of a union official.
Royal Mail advised customers to post outside the Oxford area. The union said it had renounced the strike.
But Bob Cullen, of the Communications Workers' Union, said: "We put it to the membership to return to work today, and they unanimously voted against it.
"Between 300 to 400 workers were on strike, and of those 150 to 170 of our members attended the [members] meeting today."
Another union meeting would be held on Thursday at 1100 BST, Mr Cullen added.
In a statement, Royal Mail said it was "extremely disappointed that staff have elected to ignore the proper processes for handling these matters and have instead walked out without notice".
It added: "The unofficial local action will cause further financial loss and impact on the quality of service we provide to our customers.
"Royal Mail remain available at anytime to discuss the issue at the centre of the dispute, which is being handled in accordance with procedures agreed with the CWU."
Just over 20% of staff have worked normally since the action began on Monday afternoon.
Royal Mail has called on the union to encourage staff to return to work as soon as possible and has apologised to customers for the disruption.
Mr Cullen said one suspension followed a complaint from a member of the public, and that talks between the two parties to resolve the action broke down on Monday night.
The Oxford Mail Centre handles all post coming into Oxfordshire. A week-long unofficial strike two years ago caused massive disruption to services.