More than two weeks of strike action by UPS drivers working on an Argos contract are due to start this month with a long-running pay dispute showing no signs of being resolved.

The Unite union warned there would be severe disruption for the retailer if shunter and HGV drivers at the Barton distribution centre stopped working from the 17 December and it urged UPS to table “a sensible offer”.

The union said its pay claim submitted in March had been continually disregarded and that 50 drivers were therefore prepared to down tools and commence 15 days of strike action at the flagship Burton-on-Trent site.

It said the treatment of the drivers had been “disgraceful” and claimed that the only attempt at engagement was the offer of a voucher scheme that was so lacking in detail it could not be put to members in a ballot.

It added that the situation was compounded by Argos insisting that the pay claim could not be lodged, because the workers were midway through a previously agreed two-year pay deal, before acknowledging that the claim was valid.

Unite regional officer Rick Coyle said: “Unite has been waiting for an offer in response to our members pay claim since March. Drivers and shunters have been treated with contempt and have had enough.

“The treatment of these Barton workers has been disgraceful. The reputations of UPS and Argos are at risk during the peak Christmas period because of this refusal to meaningfully engage with the pay claim.”

However, a UPS spokesman said contingency plans would be put in place to minimise disruption: “Discussions with Unite are ongoing and we remain hopeful that a mutually satisfactory agreement can be reached,” he added.

Argos said it was a matter between UPS and its employees and that “we have plans in place to maintain continuity of supply".