A strike at Argos' distribution centres will "severely hit" the retailer's customers, a union has said.
Unite members have begun a strike over what the union says is Argos' failure to negotiate a national deal covering redundancy and severance packages.
It has accused Argos of failing to guarantee that workers' future terms and conditions will be safeguarded.
However, Argos insists that its contingency plans mean customers will not be affected.
The strike, due to continue until Tuesday 5 September, covers five sites: Basildon in Essex, Bridgwater in Somerset, Castleford in West Yorkshire, Heywood in Greater Manchester and Burton-on-Trent.
Unite said that because Argos works on a "just-in-time" delivery policy - keeping the minimum amount of stock on its shelves - the smallest disruption could upset the supply chain.
But an Argos spokesperson said: "Customers will not be impacted and should be reassured that full contingency plans are in place.
"We're disappointed with the union's actions, which are based on unreasonable demands and are wholly unnecessary. This dispute isn't about pay and benefits. It's not about job losses. The union has made a series of demands based on entirely theoretical scenarios."
Workers voted to strike after Argos, now owned by supermarket giant Sainsbury's, transferred 500 workers from Argos' Lutterworth distribution hub in Leicestershire to Wincanton Logistics, 25 miles away in Kettering, Northamptonshire.
Matt Draper, Unite national officer for logistics and retail distribution, said: "What we are faced with is the thin end of the wedge with Sainsbury's pulling the strings behind the scenes - and that the not-so-hidden agenda is serious cost-cutting to the detriment of our members.
"The transfer of the workers from Lutterworth to the Wincanton site at Kettering, whether they wanted to go or not, led to this strike ballot."