(Reuters) - Russian forces intensified their offensive in Ukraine's eastern Donbas region using artillery, rocket-launchers and aircraft to damage defences around Donetsk, Ukraine's general staff said on Friday.

"The Russian enemy carried out massive artillery shelling of civilian infrastructure, including multiple rocket-launchers," it said in a statement.

Russian shelling in Luhansk, also in the Donbas, has killed 13 civilians over the past 24 hours, regional governor Serhiy Gaidai said.

Twelve were killed in the town of Sievierodonesk, where a Russian assault had been unsuccessful, he said.

Ukraine's Prosecutor General office said 232 children had been killed and 427 wounded since the beginning of Russian invasion.

Reuters could not independently verify the reports and Russia denies targeting civilians.

The industrial Donbas region, the focus of recent Russian offensives, has been destroyed, President Volodymyr Zelenskiy said, as some of the world's richest countries pledged to bolster Kyiv with billions of dollars.

Since turning away from Ukraine's capital, Russia is using massed artillery and armour to try to capture more territory in the Donbas, comprised of the Donetsk and Luhansk areas, which Moscow claims on behalf of separatists.

"The occupiers are trying to exert even more pressure. It is hell there - and that is not an exaggeration," Zelenskiy said in an address on Thursday night. There were also "constant strikes" on the Odesa region in the south, he said.

"The Donbas is completely destroyed," he said.

Moscow calls its invasion a "special military operation" to rid Ukraine of fascists, an assertion Kyiv and its Western allies say is a baseless pretext for an unprovoked war.

Russia is likely to reinforce its operations Donbas region once it secures the southern port city of Mariupol, scene of a weeks-long siege, British military intelligence said.

As the invasion nears the three-month mark, the U.S. Senate on Thursday overwhelmingly approved nearly $40 billion in new aid for Ukraine, by far the largest U.S. aid package to date.

The Group of Seven rich nations also agreed to provide Ukraine with $18.4 billion. Ukraine said the money would speed up victory over Russia and was just as important as "the weapons you provide".

The White House is working to put advanced anti-ship missiles in the hands of Ukrainian fighters to help defeat Russia's naval blockade, officials said.

U.S. Secretary of State Antony Blinken accused Russia of using food as a weapon by holding "hostage" supplies for not just Ukrainians, but also millions around the world. 

The war has caused global prices for grains, cooking oils, fuel and fertiliser to soar.