Ukrainian president Volodymyr Zelensky has suggested allowing unoccupied parts of his country to join Nato could help end the “hot phase” of its war with Russia.
Speaking to Sky News, the Ukrainian leader said that such a proposal has "never been considered" by Ukraine because it has never "officially" been offered.
Speaking via a translation transmitted by Sky News, Mr Zelensky said: "If we want to stop the hot stage of the war, we should take under Nato umbrella the territory of Ukraine that we have under our control.
"That's what we need to do fast, and then Ukraine can get back the other part of its territory diplomatically.
"This proposal has never been considered by Ukraine because no one has ever offered that to us officially."
In the same interview, Mr Zelensky also said that any invitation should be given "within its internationally recognised border, you can't give invitation to just one part of a country".
US President-elect Donald Trump has vowed to stop the war between Russia and Ukraine “within a day” of taking power in January, without setting out how he would achieve that.
Mr Zelensky himself has endorsed a push to broker a deal to end the near-three-year war at some point in 2025.
Ukraine's renewed push to secure an invitation to join Nato is part of a "victory plan" outlined last month by Mr Zelensky to end the war triggered by Russia's invasion.
Ukrainian Foreign Minister Andrii Sybiha urged his Nato counterparts to issue an invitation at a meeting in Brussels next week to Kyiv to join the Western military alliance, according to a letter seen by Reuters on Friday.
Kyiv says it accepts that it cannot join the alliance until the war is over but extending an invitation now would show Putin that he could not achieve one of his main goals - preventing Kyiv from becoming a Nato member.
"The invitation should not be seen as an escalation," Mr Sybiha wrote in the letter.
"On the contrary, with a clear understanding that Ukraine's membership in Nato is inevitable, Russia will lose one of its main arguments for continuing this unjustified war," he wrote.
"I urge you to endorse the decision to invite Ukraine to join the Alliance as one of the outcomes of the Nato Foreign Ministerial Meeting on 3-4 December 2024."
Nato diplomats say there is no consensus among alliance members to invite Ukraine at this stage. Any such decision would require the consent of all Nato's 32 member countries.
Mr Zelensky’s interview comes in the same week that Russian drone and missile attacks have hit civilian infrastructure in Ukraine, leaving more than a million people without heat and power in freezing temperatures.
Prime Minister Sir Keir Starmer discussed the attacks with Mr Zelensky in a call on Thursday.
Downing Street said the leaders "discussed the egregious Russian missile strike in the early hours of this morning, which had deprived more than a million people of heat, light and electricity".
The Prime Minister described the "systemic attacks on Ukraine's energy sector" as "depraved", No 10 said.
Following reports that a fresh consignment of Storm Shadow missiles have been sent to Kyiv, Mr Zelensky said in his call with Sir Keir "we discussed advancing our defence cooperation and strengthening Ukraine's long-range capabilities".