The Russian military alleged Thursday that its forces have managed to capture more of the outer neighbourhoods of Mariupol, in southeastern Ukraine, saying the operation to "liberate" the strategic port city is ongoing.

The claim came a day after a Russian airstrike destroyed a children’s hospital and maternity ward in Mariupol, where heavy fighting has been taking place in recent days.

Local authorities in the besieged city have accused Russian forces of waging a "medieval siege" against them.

-ABC News' Patrick Reevell

The top diplomats from Russia and Ukraine are meeting now in Antalya, Turkey.

Russian Foreign Minister Sergey Lavrov and Ukrainian Foreign Minister Dmytro Kuleba arrived in the southern Turkish resort on Thursday morning ahead of the meeting -- the highest level talks between their two countries since Russia invaded Ukraine on Feb. 24.

Both officials first met separately with their Turkish counterpart, Mevlut Cavusoglu, upon arrival. Cavusoglu is expected to attend their talks.

Lavrov and Kuleba are expected to talk for about 90 minutes. They will hold separate press conferences afterwards.

-ABC News' Engin Bas and Joe Simonetti

Russia’s foreign ministry has claimed that Ukraine put firing positions inside the children’s hospital and maternity ward in Mariupol, Ukraine, that was destroyed by shelling Wednesday.

There is currently no evidence to support the claim, made by Foreign Ministry spokeswoman Maria Zakharova during a daily briefing Wednesday. The comment appears to be an implicit acknowledgment that Russia deliberately targeted the hospital, as Ukrainian officials had claimed.

Independent investigations found that in Syria, Russia’s air force deliberately bombed hospitals in rebel-held areas as a tactic of war.

-ABC News' Patrick Reevell

The State Department spoke out against the Kremlin's allegations of U.S. chemical or biological weapons activity in Ukraine.

"Russia has a track record of accusing the West of the very crimes that Russia itself is perpetrating," State Department spokesperson Ned Price said in a statement Wednesday, calling the allegations of U.S. biological weapons labs and chemical weapons development in Ukraine "outright lies," "conspiracy theories," "disinformation" and "total nonsense."

"Russia is inventing false pretexts in an attempt to justify its own horrific actions in Ukraine," he continued. "The United States does not own or operate any chemical or biological laboratories in Ukraine, it is in full compliance with its obligations under the Chemical Weapons Convention and Biological Weapons Convention, and it does not develop or possess such weapons anywhere."

-ABC News' Conor Finnegan

U.S. Secretary of State Antony Blinken crossed the border into Ukraine Saturday after meeting with Ukrainian Foreign Minister Dmytro Kuleba at the Korczowa Border Crossing Point.

"The entire world stand with Ukraine," Blinken said, and Kuleba added that he hopes Ukrainians will see this as a "clear manifestation that we have friends who literally stand by us."

Blinken said the sanctions imposed so far against Russia are "producing very, very concrete results" and that the pressure will "grow" until this "war of choice is brought to an end."

When asked directly about helping Kuleba with more firepower, Blinken said, "the support for Ukraine not only has been unprecedented, not only is going to continue, it's going to increase."

Kuleba said Ukraine "appreciates" sanctions that have been announced in the last week, but that more economic and political pressure and "necessary weapons," would "save many lives in Ukraine... many sufferings will be avoided."

Kuleba also said that they are “satisfied" with already arranged supplies of anti-tank weapons and ammunition, but that “it’s no secret” they still want fighter jets and air defense systems.

He also thanked the U.S. for sending stingers, and said they were used on Saturday.

"Just today we shot down three Russian attack aircrafts, which were bombing our cities with the use of stingers but we need -- so to say -- big air defense systems to ensure the safety of our skies. If we lose the skies, there will be much, much more blood on the ground,"Kuleba said.

In response to questions about NATO’s refusal to impose a no-fly zone over Ukraine, Kuleba said it’s a "sign of weakness," but stayed optimistic that they will change their minds.

"The time will come," he said.

-ABC News' Conor Finnegan and Justin Gomez