Ukrainian Foreign Minister Dmytro Kuleba on Wednesday ruled out ceding territory to Russia as part of any peace deal and said no peace talks were under way between Moscow and Kyiv.

"The objective of Ukraine in this war... is to liberate our territories, restore our territorial integrity, and full sovereignty in the east and south of Ukraine," he told a briefing. "This is the end point of our negotiating position."

Russia, which invaded Ukraine on Feb. 24, took control of Luhansk province in eastern Ukraine this month and hopes to capture all territory it does not yet control in neighboring Donetsk, the other province in the industrial Donbas region.

Kuleba said in an interview published earlier on Wednesday - before talks in Istanbul involving Ukrainian, Russian, Turkish and U.N. officials - that a deal to resume grain exports blocked by Russia appeared very close.

But he made clear at Wednesday's briefing that broader peace talks were frozen.

"Currently there are no (peace) talks between Russia and Ukraine because of Russia's position and its continued aggression against our country," Kuleba said.

Asked about a decision by the Canadian government to return a repaired turbine to Germany that is needed for the Nord Stream 1 gas pipeline between Russia and Germany, Kuleba said Kyiv had told Berlin and Ottawa that this was a "mistake."

The Canadian government said on Saturday said it was issuing a "time-limited and revocable permit" to exempt the return of turbines from its Russian sanctions as Europe seeks continued energy flows until it can end its dependency on Russian gas.