This photo shows towers and cathedrals of the Kremlin in Moscow. AFP
"This topic is so complex, connected with a settlement, that, of course, probably it is not worth setting any rigid time frames and trying to get a settlement, a viable settlement, in a short-time frame," Kremlin spokesman Dmitry Peskov told state TV.
On the other hand, Ukraine's allies will meet in London on Wednesday, a senior Kyiv official told AFP, as the United States pushes for a ceasefire more than three years into the Russian invasion.
There has been a flurry of diplomatic manoeuvering since Donald Trump returned to the White House in January, as European leaders scramble to work out how they can support Ukraine should Trump pull Washington's backing.
The Wednesday talks come after Russia resumed its aerial attacks following a brief Easter truce.
Russia hit the southern city of Zaporizhzhia with "two guided aerial bombs" on Tuesday, killing one and wounding 13, the regional head said.
"One guided aerial bomb hit an infrastructure facility, another one hit a densely populated neighbourhood, a residential building directly," Governor Ivan Fedorov said on Telegram.
The London talks are a follow-up to last week's meeting in Paris where US Secretary of State Marco Rubio presented Washington's plan for ending the war.
The Ukrainian source, who spoke on condition of anonymity, did not say who from Ukraine would attend.
Trump has been pushing for a ceasefire but has failed to extract any major concessions from Russian President Vladimir Putin.
The United States and Europe rushed to Ukraine's aid when Russia invaded in February 2022, providing arms and finance to help it defend against Moscow's army.
But Trump has long railed against that support -- briefly cutting intelligence sharing and arms supplies to Kyiv.
Many in Ukraine fear any settlement he brokers could reward Russian aggression.
France and Britain have responded by trying to rally Europe and assemble a "coalition of the willing" -- countries ready to send troops to Ukraine to enforce any future ceasefire.
Deal long way off
But any deal looks a long way off.
Putin on Monday threw doubt on a proposal by Ukrainian President Volodymyr Zelensky to halt aerial attacks on civilian infrastructure.
He accused Kyiv of using civilian facilities for military purposes but held open the possibility of bilateral talks with Kyiv to discuss the idea.
"There are no concrete plans (to talk), there is readiness from Putin to discuss this question," Putin's spokesman Dmitry Peskov told reporters on Tuesday.
"If we are talking about civilian infrastructure, then we need to understand, when is it civilian infrastructure and when is it a military target," he added.
Both sides reported a dip in fighting during the Easter truce.
But Kyiv and its allies accused Putin of using it as a PR exercise, saying that the Kremlin has no genuine desire to halt its invasion, which has killed tens of thousands as it grinds through its fourth year.
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