By Pavel Polityuk and Oleksandr Kozhukhar
KYIV/LVIV, Ukraine (Reuters) - Ukraine warned on Wednesday that Russia was ramping up efforts in the South and East as it seeks full control of Mariupol, in what would be the first major city to fall, while Western governments committed more military help to bolster Kyiv.
The Kremlin's nearly seven-week-long incursion, the biggest attack on a European state since 1945, has not gone to plan.
Russia has been forced to pull back from some northern areas even as attacks across the country have turned Ukrainian cities to rubble and caused more than 4.6 million people to flee abroad.
Russia's defence ministry on Wednesday said 1,026 soldiers from Ukraine's 36th Marine Brigade, including 162 officers, had surrendered in Mariupol, which has been besieged for weeks, and that the port was fully under its control.
Capturing its Azovstal industrial district, where the marines have been holed up, would give the Russians full control of Ukraine's main Sea of Azov port, reinforce a southern land corridor and expand its occupation of the country's East.
Ukraine's general staff said Russian forces were attacking Azovstal and the port, but a defence ministry spokesman said he had no information about any surrender.
"Russian forces are increasing their activities on the southern and eastern fronts, attempting to avenge their defeats," Ukrainian President Volodymyr Zelenskiy said in a Wednesday night video address.
Reuters journalists accompanying Russian-backed separatists saw flames billowing from the Azovstal area on Tuesday, a day after Ukraine's 36th Marine Brigade said its troops had run out of ammunition.
The United States announced on Wednesday an extra $800 million in military assistance including artillery systems, armoured personnel carriers and helicopters. This took total U.S. military aid to more than $2.5 billion. France and Germany also pledged more.
Russia will view U.S. and NATO vehicles transporting weapons on Ukrainian territory as legitimate military targets, Deputy Foreign Minister Sergei Ryabkov told the TASS news agency.
It will impose tit-for-tat sanctions on 398 members of the U.S. House of Representatives and 87 Canadian senators, Interfax cited the foreign ministry as saying, after Washington targeted 328 members of Russia's lower house of parliament.
Britain announced new financial measures on separatists.
'LIBERATE US FROM WHAT?'
Ukraine says tens of thousands of people are believed to have been killed in Mariupol and accuses Russia of blocking aid convoys to civilians marooned there.
Its mayor, Vadym Boichenko, said Russia had brought in mobile crematoria "to get rid of evidence of war crimes" - a statement that was not possible to verify.
Moscow has blamed Ukraine for civilian deaths and accused Kyiv of denigrating Russian armed forces.
In the village of Lubianka northwest of Kyiv, from where Russian forces had tried and failed to subdue the capital before being driven away, a message to Ukrainians had been written on the wall of a house that had been occupied by Russian troops.
"We did not want this ... forgive us," it said.
The Kremlin says it launched a "special military operation" to demilitarise and "liberate" Ukraine, a message villagers said had been repeated to them by the Russian troops.
"To liberate us from what? We're peaceful... We're Ukrainians," Lubianka resident Viktor Shaposhnikov said.
Polish President Andrzej Duda said on a visit to Kyiv with his Lithuanian, Latvian and Estonian counterparts that those who had committed and ordered crimes must be brought to justice.
Germany's president did not join them as he had planned.
Zelenskiy said there had been no official approach and one of his officials denied a newspaper report he had rejected the visit due to Steinmeier's recent good relations with Moscow.
BIDEN'S GENOCIDE COMMENTS
The Kremlin denounced President Joe Biden's description of Moscow's actions in Ukraine as amounting to genocide, with spokesman Dmitry Peskov saying this was unacceptable coming from the leader of a country he said had committed crimes of its own.
The White House said a legal process will be undertaken.
An initial report by a mission of experts set up by the Organization for Security and Cooperation in Europe documents a "catalogue of inhumanity" by Russian troops in Ukraine, according to the U.S. ambassador to the OSCE.
"This includes evidence of direct targeting of civilians, attacks on medical facilities, rape, executions, looting and forced deportation of civilians to Russia," Michael Carpenter said.
Russia has denied targeting civilians and has said Ukrainian and Western allegations of war crimes are fabricated.
The Kyiv district police chief said 720 bodies had been found in the region around the capital from where Russian forces had retreated, with more than 200 people missing.
International Criminal Court Prosecutor Karim Khan said after visiting Bucha, a town where bound bodies of people apparently shot at close range were found, that Ukraine was a "crime scene" and this was within ICC jurisdiction.
"We have to pierce the fog of war to get to the truth,” Khan said on Twitter (NYSE:TWTR).
The mayor of the northeastern city of Kharkiv, Ukraine's second largest, said bombing had increased significantly on Wednesday and satellite photos from Maxar Technologies (NYSE:MAXR) showed long columns of armoured vehicles in the region.
At least seven people were killed, including a two-year-old boy, and 22 wounded in Kharkiv over the past 24 hours. Ukrainian forces shot down two Russian planes attacking towns in the region, regional Governor Oleh Synehubov said earlier.
Reuters could not immediately verify his statement but filmed people in Kharkiv quietly carrying bodies from an apartment block hit by shelling.