Senior Ukrainian negotiators have offered to hold special talks with Russia in Mariupol without conditions in a bid to evacuate troops and civilians from the besieged port city.
Negotiator Mykhailo Podolyak tweeted on Wednesday that the talks could be "one on one. Two on two. To save our guys, (the far right) Azov (battalion), military, civilians, children, the living and the wounded".
Ukraine accused Russian forces on Wednesday of failing to observe a local ceasefire agreement long enough to allow large numbers of women, children and elderly people to flee the city, which has been largely pounded to rubble by Russian forces.
The remaining fighters holed up in vast steelworks have ignored previous ultimatums by Russia to surrender and made clear on Wednesday their stance had not changed.
David Arakhamia, a second negotiator, said in an online post that he and Podolyak were in constant contact with Ukrainian forces in the city.
"Today, in a conversation with the city defenders, a proposal was put forward to hold direct negotiations, on site, on the evacuation of our military garrison," he said. "For our part, we are ready to arrive for such negotiations at any time as soon as we receive confirmation from the Russian side."
A senior member of the Azov Battalion - which is now integrated into the Ukrainian armed forces and leading the defence of Mariupol - earlier said the defenders had rejected Russia's two-day-old demand to down weapons.
They sought instead an agreement to allow civilians to leave but said constant Russian shelling and a failure to uphold a ceasefire had made an evacuation impossible.
"I therefore call for these guarantees to be upheld. Only with the help of a third party can the civilians leave the plant," Azov's deputy commander, Svyatoslav Palamar, said in a video appeal.
Azov, he said, had asked Podolyak and Arakhamia to come to the city for talks along with top Russian negotiators.
"Let me say that we do not accept the conditions set down by the Russian Federation on giving up our weapons and our defenders giving themselves up as prisoners," Palamar said.