If the West wants to fight for Ukraine on the battlefield, Russia is prepared for it, acting Russian Foreign Minister Sergei Lavrov was quoted as saying on Monday.

"It's their right — if they want it to be on the battlefield, it will be on the battlefield," state-run news agency RIA cited Lavrov as saying.

Russia has stepped up warnings about the dangers of a direct confrontation with NATO since French President Emmanuel Macron refused to rule out the possibility that Western troops could at some point be sent there.

The Kremlin said last week that sending NATO troops into Ukraine would potentially be extremely dangerous. President Vladimir Putin has said it could lead to World War III.

Lavrov, who has served two decades as foreign minister, was speaking at a parliamentary hearing on his renomination to the post in a new government being formed after Putin started a fresh six-year term this month.

RIA also cited him as saying that peace talks on Ukraine due to take place in Switzerland next month without Russia's participation amounted to an ultimatum to Moscow.

He compared the situation to "a reprimand for a schoolchild" whose fate was being decided by teachers while he was out of the room, the agency said.

"You can't talk to anyone like that, especially to us," Lavrov said. "The conference... boils down to restating an ultimatum to Russia."