Ukraine has reacted with scepticism to Russia's promise to scale down military operations around Kyiv and another city as some Western countries expected Moscow to intensify its offensive in other parts of the country.
Talks took place in an Istanbul palace more than a month into the largest attack on a European nation since World War II that has killed or injured thousands, forced nearly 4 million to flee abroad and pummelled Russia's economy with sanctions.
The invasion has been halted on most fronts by stiff resistance from Ukrainian forces that have recaptured territory even as civilians are trapped in besieged cities.
"In order to increase mutual trust and create the necessary conditions for further negotiations and achieving the ultimate goal of agreeing and signing [an] agreement, a decision was made to radically, by a large margin, reduce military activity in the Kyiv and Chernihiv directions," Russian Deputy Defence Minister Alexander Fomin told reporters.
He made no mention of other areas that have seen heavy fighting, including around Mariupol in the south-east, Sumy and Kharkiv in the east, and Kherson and Mykolaiv in the south.
While Moscow portrayed it as a goodwill gesture, its ground troops have become bogged down and taken heavy losses in their bid to seize Kyiv and other cities.
Last week, and again on Tuesday, the Kremlin seemed to lower its war aims, saying its "main goal" now was gaining control of the mostly Russian-speaking Donbas region in eastern Ukraine.
The negotiations were expected to resume on Wednesday in Istanbul.
Ukranian shell reportedly strikes camp inside Russia
As both sides prepared for further talks, a shell hit a temporary Russian military camp near the border with Ukraine late on Tuesday, Russia's TASS news agency said.
It cited a source as saying preliminary data showed it had been fired from the Ukrainian side.
TASS issued the report shortly after a senior local official reported a series of explosions outside the city of Belgorod, close to the border with Ukraine.
Video posted online from two local Belgorod news outlets appeared to show ammunition blowing up in the distance but Reuters was not immediately able to confirm this was the case.
TASS cited an emergency services source as saying four people had been injured in the blast.
Belgorod governor Vyacheslav Gladkov earlier said the blasts occurred near the village of Krasny Oktyabr, about 30 kilometres south-west of Belgorod.
Belgorod is 80km north of the Ukrainian city of Kharkiv, which Russian forces have bombarded heavily in recent weeks.
Statements 'don't silence the explosions': Zelenskyy
Ukrainian President Volodymyr Zelenskyy said there was no reason to believe Russia's announcement, given what's still happening on the ground.
"Ukrainians are not naive people," he said.
"We can call those signals that we hear at the negotiations positive. But those signals don't silence the explosions of Russian shells.
"Ukrainians have already learned during these 34 days of invasion, and over the past eight years of the war in Donbass, that the only thing they can trust is a concrete result."
Mr Zelenskyy said it was Ukrainian troops who forced Russia's hand, adding that "we shouldn't let down our guard" because the invading army can still carry out attacks.
Russia has started moving very small numbers of troops away from positions around Kyiv in a move that is more of a repositioning than a retreat or a withdrawal from the war, the Pentagon said on Tuesday.
"We all should be prepared to watch for a major offensive against other areas of Ukraine," spokesman John Kirby said.
"It does not mean that the threat to Kyiv is over."
Britain's Ministry of Defence in an intelligence update said: "It is highly likely that Russia will seek to divert combat power from the north to their offensive in the Donetsk and Luhansk regions in the east."
Reuters could not immediately verify the claims made by either side.
The Moscow-backed self-proclaimed Donetsk People's Republic in eastern Ukraine may consider joining Russia once it controls all of Ukraine's Donetsk region, its leader was quoted as saying.
Kyiv has said any such move would have no legal basis.
Putin to review Ukraine's proposals
Ukrainian negotiators said that under their proposals, Kyiv would agree not to join alliances or host bases of foreign troops, but would have security guaranteed in terms similar to "Article 5", the collective defence clause of the transatlantic NATO military alliance.
They named Israel and NATO members Canada, Poland and Turkey as countries that may give such guarantees.
Russia, the United States, Britain, Germany and Italy could also be involved.
The proposals, which would require a referendum in Ukraine, mentioned a 15-year consultation period on the status of Crimea, annexed by Russia in 2014.
The fate of the south-eastern Donbass region, which Russia demands Ukraine cede to separatists, would be discussed by the Ukrainian and Russian leaders.
Kyiv's proposals also included one that Moscow would not oppose Ukraine joining the European Union, Russia's lead negotiator Vladimir Medinsky said.
Russia has previously opposed Ukrainian membership of the EU and especially of NATO.
Mr Medinsky said Russia's delegation would study and present the proposals to Mr Putin.
To prepare a peace agreement, Mr Medinsky later told the TASS news agency: "We still have a long way to go."
Some analysts noted that Russia's promise to reduce fighting mostly covered areas where it has been losing ground.
The general staff of the Ukrainian armed forces said Russia's promise to curtail military operations in some areas was "probably a rotation of individual units and aims to mislead."
The Russian military accused Ukrainian forces in cities under attack of using ceasefires to restore their combat readiness and set up firing points in hospitals and schools, Interfax news agency said.
Biden to meet with other Western leaders
In Ukraine's besieged seaport Mariupol, thousands of civilians may have died, the head of the United Nations human rights mission in the country told Reuters on Tuesday.
Those who remain are suffering.
"We are eight people. We have two buckets of potatoes, one bucket of onions," said Irina, an engineer, in her apartment where windows had been blasted out.
Elsewhere, Ukrainian forces have made advances, recapturing territory from Russian troops on the outskirts of Kyiv, in the north-east and in the south.
In the southern city of Mykolaiv, a missile blasted a hole through the main administrative building. Authorities said at least 12 people were killed and 33 injured.
US President Joe Biden will talk to the leaders of France, Germany, Italy and Britain to discuss the latest developments in Ukraine, the White House said.
French President Emmanuel Macron is scheduled to talk to Russian President Vladimir Putin.
Russian Foreign Minister Sergei Lavrov and US deputy national security adviser for economics, Daleep Singh, will both visit India, which has called for a ceasefire but has refused to explicitly condemn Moscow.
ABC/Wires
