Ukraine's president says he hopes fighters still trapped in a Mariupol steel plant can be saved.
It is thought that around 2,000 Ukrainian soldiers remain in tunnels underneath the Azovstal plant, where they have been holed up for weeks as Russian forces move further into the southern port city.
They are the last pocket of resistance in an area almost destroyed, and they have repeatedly refused to surrender.
Their cause has appeared almost hopeless, however - many of them are injured, with little or no ammunition left, and severe shortages of food, water, and electricity.
But during his nightly address on Friday, Volodymyr Zelenskyy said: "We are working on diplomatic options to save our military who still remain at Azovstal.
"Influential mediators are involved.
He gave no further details.
In other key developments:
• Western officials say Russia has made the "unusual" move of not inviting foreign leaders to celebrate Victory Day next week, a day which marks the Soviet victory over Nazi Germany in 1945
• US President Joe Biden authorised the shipment of another $150m in military assistance for Ukraine, including artillery rounds and radar systems
• Russian troops continue to struggle - their focus is the south-eastern region of Donbas, but Ukraine said its forces had repelled 11 attacks in the area, something Russia did not confirm
• A number of cities, including Odesa, have implemented curfews and increased street patrols ahead of Russia's Victory Day. Ukrainian officials have warned that Russian attacks could increase on the patriotic holiday
• Ukraine said it has made progress in the north-eastern Kharkiv region, recapturing five villages and part of a sixth
• Russia said two self-proclaimed separatist republics in Ukraine's east - Donetsk People's Republic and Luhansk People's Republic - appointed ambassadors to Moscow. Ukraine's foreign ministry spokesman said they were "traitors" and will likely be charged with treason
It came after dozens of civilians were evacuated from the steel plant on Friday afternoon with officials from Ukraine and Russia vowing to continue the evacuations on Saturday.
Mariupol's mayor said earlier this week that 200 civilians were trapped at the plant - a small fraction of the 100,000 people thought to still be in the city from its pre-war population of 400,000.
Earlier on Friday, Mr Zelenskyy spoke at an event hosted by the Chatham House think tank in London, saying that there is still the possibility of negotiations with Russia.
He said bridges between the two countries are not yet "destroyed", and that arrangements were needed for talks to "stop the killing".
But he said these talks could only take place if Moscow withdrew its troops, adding that he had not been elected to lead a "mini-Ukraine of some kind".
"They have to fall back," he added.
"In that situation we will be able to start discussing things normally."
He said that "despite the fact that they are destroying all our bridges, I think not all the bridges are yet destroyed".