Kyiv will make the demand 10 months into Moscow's offensive and as Russia's defiant leader Vladimir Putin accused the West of trying to "tear apart" his country.  

Russia on Monday said it downed a Ukrainian drone at its Engels airfield -- more than 600 kilometres (370 miles) from the Ukraine border. 

Russian news agencies, quoting the defence ministry, said three people were killed by debris. 

Moscow has blamed Ukraine for attacks on its territory and Moscow-annexed Crimea before but this marked the second attack on the Engels airfield this month and the deepest strike into Russian territory so far since the February offensive. 

There was no comment as yet from Kyiv. 

On Sunday, Ukrainian Foreign Minister Dmytro Kuleba said Kyiv will call for Russia to be stripped of its permanent membership of the UN Security Council, which it sits on with the US, the UK, France and China. 

"Tomorrow we will officially express our position. We have a very simple question: Does Russia have the right to remain a permanent member of the UN Security Council and to be in the United Nations at all?" Kuleba said. 

"We have a convincing and reasoned answer -- no, it does not."

The five permanent members of the powerful 15-seat Security Council have veto power that can block any resolution. 

- 'Unite the Russian people' -

On Sunday, a pugnacious Putin said his offensive in Ukraine aimed to "unite the Russian people", accusing his country's "geopolitical opponents (of) aiming to tear apart Russia, the historical Russia".

Putin has used the concept of "historical Russia" to argue that Ukrainians and Russians are one people -- undermining Kyiv's sovereignty and justifying his 10-month offensive in Ukraine.

"Divide and conquer, that's what they have always sought to accomplish and are still seeking to do," Putin said in a television interview.

"But our goal is different: it's to unite the Russian people."

He repeated that Moscow was ready to negotiate and appeared unfazed when asked about a new air defence system the United States will deliver to Ukraine.

"Of course we will destroy it, 100 percent!" Putin said, referring to the Patriot missile battery promised to Ukrainian President Volodymyr Zelensky.

Zelensky last week earned firm pledges of support from Washington during his first trip out of Ukraine since the conflict began -- including the Pentagon's most advanced air defence system.

Western military and financial aid has been crucial for Ukraine's pushback of Russian troops -- including from Kherson, the only regional capital that was held by Russia. 

Despite Russia's retreat from the city, it remains within reach of Moscow's weaponry and under constant threat.

- Defiant Christmas -

On Sunday, church bells pealed throughout Kyiv as Orthodox Christians attended Christmas services, in a break with the Russian spiritual leaders who will mark the holiday in two weeks.

At a service in central Kyiv, worshipper Olga Stanko told AFP she supported any move that would distance Ukraine from Russia. 

"The war has brought us so much grief," she said. "We cannot do this with Russia, remain under its influence."

The decision by some Ukrainian churches to observe Christmas on December 25 highlights the deepening rift between religious leaders in Kyiv and Moscow. 

Ukraine had been under Moscow's spiritual leadership since at least the 17th century, but part of the Ukrainian Orthodox Church broke with Moscow in 2019 over Russia's annexation of Crimea and support for separatists in the east. 

In May, the Russia-backed branch of Ukraine's Orthodox Church also severed ties with Moscow.