Russia's defense ministry said on Tuesday it had offered Ukrainian fighters sheltering in the Azot chemical plant in the eastern Ukrainian town of Sievierodonetsk the chance to surrender on June 15, the Interfax news agency reported.
Russia said on Tuesday "Guided by humane principles, the Armed Forces of Russia and the formations of the Lugansk People's Republic are ready to" open a humanitarian corridor from 08:00 on Wednesday (0500 Israel time) to allow civilians to leave, and urged Ukrainian fighters to "stop their senseless resistance and lay down their arms" at the same time.
"The safe evacuation of all civilians without exception and their movement as part of humanitarian convoys to temporary accommodation centers is guaranteed," the head of the National Defense Control Center of the Russian Federation Mikhail Mizintsev said Tuesday Interfax news agency reported.
The ministry said Ukraine had asked Russia to set up an evacuation corridor to help civilians leave the plant, with all the bridges linking Sievierodonetsk to Ukrainian-held territory now destroyed.
In the statement announcing the call to surrender, Russia's Defence Ministry accused Ukrainian fighters of using the civilians in the Azot plant as human shields. Moscow has made similar accusations, rejected by Kyiv, several times since it sent its troops into Ukraine in February.
The Defence Ministry said it had informed Kyiv of its offer and urged the authorities to give the order to surrender.
The situation at the Azot ("Nitrogen") plant echoes the battles that raged earlier in the conflict over the Azovstal steel works in Mariupol, where hundreds of fighters and civilians took shelter from Russian shelling. Those inside eventually surrendered and were taken into Russian custody in mid-May.
Reported casualties in Donetsk
At least five people were killed on Monday in the Russian-backed separatist Ukrainian region of Donetsk in what separatist officials said has been an upsurge in Ukrainian shelling, TASS reported.
Separatist officials and Russian news agencies reported several Ukrainian artillery strikes, including on a market. Russian news agencies later reported a shell had fallen on a maternity hospital in the city of Donetsk, triggering a fire and prompting staff to send patients into the basement.
There was no independent confirmation of any of the attacks and Reuters could not ascertain whether they had taken place. There has been no immediate reaction from Kyiv to the reports.
Donetsk's separatist leader Denis Pushilin pledged to mobilize more Russian forces to counter Ukraine.
Russian agencies reported that a child was among those killed.
"Thanks to the quick action of staff, there were no injuries," RIA news agency said.
UN spokesman Stephane Dujarric said officials had seen reports of the hospital attack.
"This is extremely troubling," Dujarric said.
"Any attack on civilian infrastructure, especially health facilities, is a clear violation of international law."
UN Spokesman Stephane Dujarric
The Donetsk News Agency earlier showed pictures of burning stalls at the Maisky market and several bodies on the ground.
"We had a hit to the market - there were many people here," Yan Gagin, an adviser to the separatists' self-styled government, told RIA news agency from the market.
Further fighting
Russia struck an artillery weapons depot with Kalibr cruise missiles in Ukraine's Chernihiv region, the RIA news agency reported, citing the Russian defense ministry.
Russian air defense forces shot down a Ukrainian MiG-29 fighter jet and an Mi-24 helicopter, the TASS news agency reported, citing the ministry.
Fighting continued in Sievierodonetsk on Tuesday, according to Kyiv independent, as well as in various villages in Donetsk Oblast.
Kremlin leader Vladimir Putin has repeatedly said that the main immediate reason for what he casts as a "special military operation" in Ukraine is to protect the Russian-speakers of the two regions in Donbas from persecution and attack by Ukraine.
Ukraine routinely denies carrying out any attacks on the two regions, the Donetsk and Luhansk People's Republics, where separatists seized large swathes of land in 2014.
Ukraine and its Western backers say Russia is waging an unprovoked war against a sovereign state.
Russia denies targeting civilian sites in its military action, though the incursion has caused thousands of casualties and destroyed entire Ukrainian towns.