BBC News ------------ Visvaldas Kulbokas was summoned by Ukraine after the Pope's comments over the need to negotiate with Russia
Ukraine has summoned the Vatican's envoy after the Pope said the country should "have the courage to raise the white flag" against Russia.
Apostolic Nuncio Visvaldas Kulbokas was told Kyiv was "disappointed" by the remarks, the foreign ministry said.
Meanwhile, President Volodymyr Zelensky has said Ukraine's position on the battlefield was "stabilising" following recent setbacks.
That was despite aid from its allies remaining "significantly limited".
The Pope caused anger in Ukraine when a transcript of an interview with Swiss broadcaster RSI, which is due to be broadcast next week, was released.
According to a transcript quoted by Reuters news agency, the Pope said: "The strongest one is the one who looks at the situation, thinks about the people and has the courage of the white flag, and negotiates."
White flags are traditionally a symbol of surrender on the battlefield.
A Vatican spokesman later said the Pope was speaking of stopping the fighting through negotiation, not capitulation.
Nevertheless, Ukraine has sought to make its displeasure known.
In a statement about the summoning of Archbishop Kulbokas, the foreign ministry "noted that instead of appeals that legalise the right of the strong and encourage them [Russia] to further disregard the norms of international law, the head of the Holy See would be expected to send signals to the world community about the need to immediately join forces to ensure the victory of good over evil, as well as appeals to the attacker, not to the victim."
Ukraine has been keen to dispel any suggestion that it would capitulate to Russia more than two years after the invasion.
"This is the period of our maximum concentration, our maximum initiative to ensure that it is Ukraine that determines a just end to this war," Mr Zelensky said in his nightly address on Monday.
"We can endure. We have to win."
Earlier in the day, the president told French broadcaster BFM TV that Ukraine had "stopped the Russian advance in eastern Ukraine".
That claim has not been verified.
Mr Zelensky also said that Ukraine was building defensive fortifications stretching 2,000km (1,243 miles) in an attempt to "meet the threats" posed by Russia.
This included "shoring up the existing fortifications and creating new ones".
His comments come as intelligence experts told US senators on Monday that the momentum in the war had swung in Russia's favour and that without further assistance, Kyiv would likely lose "significant ground" in 2024.
"The Ukrainians are not running out of courage and tenacity," Central Intelligence Agency, CIA, Director William Burns testified to the Senate Intelligence Committee.
"They're running out of ammunition, and we're running out of time to help them."
The US has been Kyiv's biggest backer in the war but aid has stalled. Congress remains gripped in a deadlock about a $95bn (£75bn) foreign aid bill - including $60bn in military assistance to Ukraine.
There are also concerns a change in president at this year's US election will see aid dry up completely.
Last month, Ukraine's defence minister said half of all Western aid for Ukraine has been delayed, costing lives and territory.
Mr Zelensky has blamed both the late start to last year's largely failed counter-offensive and the recent loss of the key eastern town of Avdiivka on faltering weapon supplies.