Russia on Thursday accused Ukrainian negotiators of changing demands since last month's talks in Istanbul, claiming that Kyiv was not interested in ending fighting.
Russian and Ukrainian negotiators met in Istanbul in March but there have been few signs of the conflict abating on the ground.
Russian Foreign Minister Sergei Lavrov said that on Wednesday the Ukrainian side had presented its draft agreement.
"It shows a departure from the most important provisions spelled out at the meeting in Istanbul on March 29," he said.
In Turkey, "the Ukrainians clearly stated that future (international) security guarantees for Ukraine do not apply to Crimea and Sevastopol," Lavrov said, referring to territory Moscow annexed in 2014.
"In yesterday's draft, this clear statement is missing," he added.
He also said that Ukrainians wanted the leaders of Russia and Ukraine to discuss Crimea and separatist-held territory in eastern Ukraine face-to-face.
"At the next stage, the Ukrainian side will certainly ask for the withdrawal of troops and will put forward new preconditions," Lavrov predicted.
"This is unacceptable."
He accused Ukrainian authorities of seeking to scupper talks and not wanting to end more than a month of fighting.
"We see this as a manifestation of the fact that the Kyiv regime is controlled by Washington and its allies, who are pushing President Volodymyr Zelensky to continue hostilities," Lavrov said.