KIEV — Ukraine accused Russia on Monday of blocking Ukrainian cheese imports for political reasons in an escalation of a food-quality dispute.

Russian consumer goods watchdog Rospotrebnadzor barred imports of cheese made by three Ukrainian producers last week after accusing them of using excessive quantities of palm oil, a cheap substitute for milk.

Ukrainian producers deny this, and officials from both sides agreed Thursday to resolve the issue by having Rospotrebnadzor inspect their facilities together with the Ukrainian authorities.

After the agreement was announced, Ukrainian Prime Minister Mykola Azarov said the conflict was a result of lobbying by Russian dairy producers, while Ukrainian Foreign Minister Kostyantyn Hryshchenko said it would hurt Russian consumers above all.

Rospotrebnadzor head Gennady Onishchenko then called off the agreement on joint inspections, triggering another angry response from Kiev.

Russia accounted for 80 percent of Ukrainian cheese exports last year, or $350 million in revenues, according to Ukrainian business weekly Delovaya Stolitsa.

Moscow has long urged Kiev to join the Customs Union it has established together with ex-Soviet allies Belarus and Kazakhstan.

But Ukraine has refused, pursuing a free trade deal with the European Union instead, which it hopes to sign this year.

"This cheese war fits within the overall theme of [Russia] putting pressure on Ukraine," said Voldymyr Fesenko, an analyst at the Ukrainian think tank Penta. "This is all tactics, and the strategy remains the same: dragging Ukraine into the Customs Union."