Ukraine said "unprecedented" air attacks had rocked its capital and other areas early Thursday, a day after it reached an agreement with Russia to extend a deal allowing grain exports across the Black Sea.
The deal, a rare example of cooperation between the warring sides, was welcomed by the United Nations and the United States, though both called for more certainty over the exports as Russia has threatened to end the pact, which is crucial to global food security.
But doubts about the viability of the deal were quickly raised after Ukraine accused Russia of launching an extraordinary series of air attacks on Kyiv and other regions early Thursday.
"A series of air attacks on Kyiv, unprecedented in their power, intensity and variety, continues," said Serhii Popko, head of Kyiv's civil and military administration, adding that no casualties had been reported in the capital.
Ukraine's army reported several explosions in Kyiv's Desnyansky district and said a fire had broken out at a business in the city's Darnytskyi neighbourhood as a result of falling debris.
The military also reported "cruise missile" attacks in the central Vinnytsia region, and local media reported explosions in Khmelnytskyi, about 100 kilometres further west.
Kyiv's anti-aircraft defences were working, according to Serhii Popko, head of the city's civil and military administration, who urged people to stay in bomb shelters.
- Air defences -
The grain deal came after Ukraine's foreign minister met China's special envoy in Kyiv, and insisted that the war-torn country would not accept any peace plan that relied on giving up territory.
China, a close ally of Moscow, has not publicly condemned Russia's invasion, and envoy Li Hui sought to promote Beijing-led negotiations to resolve the conflict.
In his meeting with Li, Foreign Minister Dmytro Kuleba stressed "Ukraine does not accept any proposals that would involve the loss of its territories or the freezing of the conflict", his ministry said.
Since Russia invaded, Western arms -- mostly from the United States -- have poured into Ukraine, including Patriot systems to help shield against relentless missile strikes targeting civilians and infrastructure.
One of only two Patriot systems confirmed to be in Ukraine was damaged by an unspecified projectile landing nearby, US officials confirmed Wednesday, though they said it was still functioning.
The Russian defence ministry said Tuesday that its forces had struck a Patriot system in Kyiv with a Kinzhal hypersonic missile, but the claim was not confirmed.
Ukraine's air defences have played a key role in protecting the country from strikes and preventing Moscow's forces from gaining control of the skies.
But as Russia faced increasing setbacks on the ground, it began air attacks that have disrupted electricity, water and heat to millions of people.
- Key Ukrainian ports -
President Recep Tayyip Erdogan of Turkey, which has a central role in the grain deal, announced the two-month extension, saying Russia had agreed not to block ships from leaving two Ukrainian ports.
"These agreements matter for global food security; Ukrainian and Russian products feed the world," UN Secretary-General Antonio Guterres said.
"I hope we will reach a comprehensive agreement to improve, expand and extend the initiative."
Russia has repeatedly threatened to pull out of the deal, which was meant to expire on May 18, and again on Wednesday denounced "disparities" in how it is implemented.
Kyiv has accused Russia of effectively still blocking its ships by refusing to register them and conducting lengthy inspections.
"It's a good thing that (the deal) has been extended," said US National Security Advisor Jake Sullivan. "Unfortunately, Russia continues even in a moment of extension to rhetorically hold it hostage in various ways."
On the ground, fighting continued for control of the eastern town of Bakhmut.
Ukraine is seeking to take back territory occupied by Russian forces in the wake of the February 2022 invasion and also areas seized by Russia in 2014.
The battle for Bakhmut has turned into the longest standoff of the war. Ukraine is now saying it is advancing in the area, retaking Russian positions in its suburbs.
In a sign of the conflict's toll on Russia's economy, the statistics agency Rosstat said Wednesday that the country's gross domestic product shrank by 1.9 percent in the first quarter of 2023.
The economy was weighed down by another wave of Western sanctions, including a ban by the European Union on Russian petroleum products, on top of an oil price cap agreed with the G7 and Australia.