Ukrainian President Volodymyr Zelensky has branded a three-day truce announced by his Russian counterpart Vladimir Putin as an "attempt at manipulation".
It comes after Mr Putin declared a three-day ceasefire to take place in May in the war with Ukraine to mark the 80th anniversary of the victory of the Soviet Union and its allies in World War II.
The Kremlin said the 72-hour ceasefire would run from 8-10 May, when Mr Putin will be hosting international leaders including Chinese President Xi Jinping for lavish celebrations to commemorate victory over Nazi Germany.
"All military actions are suspended for this period. Russia believes that the Ukrainian side should follow this example," it said in a statement.
"In the event of violations by the Ukrainian side, Russia's armed forces will give an adequate and effective response."
In response, Mr Zelensky said in his daily address: "Now there's a new attempt at manipulation: for some reason, everyone has to wait until May 8 and only then to cease fire to guarantee silence."
Ukraine's foreign minister Andrii Sybiha said Ukraine is ready to support a lasting, durable and full ceasefire, adding that if Russia truly wanted peace, it should immediately halt its attacks.
It is the second ceasefire announcement by Mr Putin in quick succession, following a 30-hour Easter ceasefire that each side accused the other of violating countless times.
Against a background of increasing impatience from the United States, both moves appeared aimed by the Kremlin leader at signalling to US President Donald Trump that Russia is still interested in peace.
Ukraine and its European allies say they do not believe this, while pushing back against US proposals they see as skewed towards Russia.
The latest announcement came after Mr Trump criticised Mr Putin for a deadly Russian attack on Kyiv last week and voiced concern at the weekend that Mr Putin was "just tapping me along".
The US has repeatedly threatened to abandon its peace efforts unless there is real progress.
Mr Zelensky, who met Mr Trump on the sidelines of Pope Francis' funeral in Rome on Saturday, has previously said Kyiv would be ready to hold talks with Moscow once a ceasefire deal has stopped the fighting.
Mr Zelensky's chief of staff, Andriy Yermak, said that continuing Russian attacks contradicted the Kremlin's statements about wanting peace.
"Russia is not ceasing fire at the front and is attacking Ukraine with Shaheds right now," Mr Yermak wrote on Telegram before the ceasefire announcement, referring to Iranian-made drones widely used by Russian forces.
"All the Russians' statements about peace without ceasing fire are just plain lies."
The Kremlin statement said: "The Russian side once again declares its readiness for peace talks without preconditions, aimed at eliminating the root causes of the Ukrainian crisis, and constructive interaction with international partners."
Kremlin spokesman Dmitry Peskov told reporters earlier that the signal for direct talks should come from Ukraine, as it currently had a "legal ban" on negotiating with Mr Putin.
He was referring to a 2022 decree in which Mr Zelensky ruled out such negotiations, after Russia had claimed four Ukrainian regions as its own in an action condemned as illegal by most countries at the United Nations.
Ukraine accuses Russia of playing for time in order to try to seize more of its territory, and has urged greater international pressure to get Moscow to stop fighting.
Russia accuses Ukraine of being unwilling to make any concessions and of seeking a ceasefire only on its own terms.
Earlier, Mr Trump said he believed Mr Zelensky was ready to concede Crimea as part of a ceasefire deal, as talks on a truce entered what Washington called a "critical" week.
Mr Trump, who boasted before his inauguration that he could halt Russia's invasion of Ukraine within one day, has launched a diplomatic offensive to stop the fighting since taking office in January.
He cast doubt on Saturday over whether Mr Putin wanted an end to the war, which has devastated swathes of eastern Ukraine and killed tens of thousands of people.
Last night, Russia launched drone and missile attacks, killing four people in regions across eastern Ukraine and wounding more than a dozen.
"I want him to stop shooting, sit down, and sign a deal," Mr Trump said last night in response to a question on what he wanted from Mr Putin.
"We have the confines of a deal, I believe, and I want him to sign it," Mr Trump added, likely referring to a US-proposed peace plan.
Earlier, US Secretary of State Marco Rubio stressed the importance of the week ahead.
"We're close, but we're not close enough" to a deal to halt the fighting, Mr Rubio told broadcaster NBC.
"I think this is going to be a very critical week."
The White House has said that without rapid progress, it could walk away from its role as a broker.
Mr Trump indicated that he would give the process "two weeks".
Crimea crucial in talks
The US has not revealed details of its peace plan, but has suggested freezing the front line and accepting Russian control of Crimea in exchange for peace.
Mr Trump said he thought Mr Zelensky was ready to concede Crimea, despite the Ukrainian leader repeatedly saying he never would.
"Oh, I think so," said Mr Trump in response to a question on whether he thought Mr Zelensky was ready to "give up" the Black Sea peninsula.
Russia, which launched its full-scale invasion of Ukraine in February 2022, claims to have annexed four eastern and southern territories of the war-battered country since then, despite not having full military control over them.
Russia holds about 20% of Ukraine's territory, including Crimea.
Germany's Defence Minister Boris Pistorius said that Ukraine should not agree to all territorial concessions to Russia reportedly set out in the deal proposed by Mr Trump.
"Ukraine has, of course, known for some time that a sustainable, credible ceasefire or peace agreement may involve territorial concessions," he told broadcaster ARD.
"But these will certainly not go... as far as they do in the latest proposal from the US president," Mr Pistorius said.
Mr Rubio had a phone call yesterday with Russia's Foreign Minister Sergei Lavrov, the foreign ministry in Moscow said.
The pair "emphasised the importance of consolidating the emerging prerequisites for starting negotiations in order to agree on a reliable path to long-term sustainable peace", a statement said.
