KYIV: The United States is prioritising efforts to boost Ukraine's air defences, President Joe Biden told his Ukrainian counterpart on Sunday, as President Volodymyr Zelenskiy stepped up efforts to secure international assistance over the Russian invasion that is dragging into a 10th month.

Heavy fighting in the country's east and south continued unabated, while drone and missile strikes on key power infrastructure, notably in the Black Sea port city of Odesa, kept many Ukrainians in the cold and dark.

There are no peace talks and no end in sight to the deadliest conflict in Europe since World War Two, which Moscow describes as a "special military operation" and Ukraine and its allies call an unprovoked act of aggression.

"We are constantly working with partners," Zelenskiy said after talking to Biden and the leaders of France and Turkey, adding that he expects some "important results" next week from a series of international events that will tackle the situation in Ukraine.

German Chancellor Olaf Scholz will hold on Monday an online meeting with G7 leaders and the European Union foreign ministers will to try to agree on further sanctions on Russia and Iran and on additional aid or arms deliveries to Ukraine.

While Zelenskiy has held numerous talks with Biden, French President Emmanuel Macron and Turkish President Tayyip Erdogan since Russian forces invaded in late February, the accumulation of discussions in just one day is not a regular event.

Zelenskiy said he had thanked Biden for "unprecedented defence and financial" help the United States has provided and talked with the U.S. president about Ukraine's need for effective anti-aircraft defence systems to protect the population.

Biden "reaffirmed the U.S. commitment to continue providing Ukraine with security, economic, and humanitarian assistance, holding Russia accountable for its war crimes and atrocities, and imposing costs on Russia for its aggression", the White House said.

U.S. Treasury Secretary Janet Yellen told CBS's "60 Minutes" Washington's support for Ukraine's military and economy - more than $50 billion and counting - would continue "for as long as it takes" and reiterated that ending the war was the single best thing the United States could do for the global economy.

TURKEY TALKS

Earlier, Zelenskiy said he held "a very meaningful" conversation with Macron on "defence, energy, economy, diplomacy" that lasted more than an hour and "very specific" talks with Erdogan on assuring Ukraine's grain exports.

Turkey, which acted as a mediator in peace talks in the early months of the war, also worked alongside the United Nations in a grain deal, which opened up Ukrainian ports for exports in July after a six-month de facto Russian blockade.

Erdogan's office said the Turkish leader had a call with Russian President Vladimir Putin on Sunday, in which he had called for a quick end to the conflict.

Putin said last week that Moscow's near-total loss of trust in the West would make an eventual settlement over Ukraine much harder to reach and warned of a protracted war.

Moscow shows no signs of being ready to respect Ukraine's sovereignty and pre-war borders, saying the four regions it claims to have annexed from Ukraine in September are part of Russia "forever." The government in Kyiv has ruled out conceding any land to Russia in return for peace.

HEAVY FIGHTING

On the ground in Ukraine, the entire eastern front line has been continuously shelled with heavy fighting taking place.

Russian forces continued with attempts to break through Ukrainian defences, training tank and artillery fire on 26 settlements near Avdiivka and Bakhmut, the General Staff of the Ukrainian Armed Forces said in a Sunday evening update.

Serhiy Gaidai, the exiled governor of the Russian-occupied Luhansk region, told Ukrainian television local forces had attacked a hotel in the town of Kadiivka where members of Russia's private Wagner military group were based, killing many of them.

Photos posted on Telegram channels showed a building largely reduced to rubble.

"They had a little pop there, just where Wagner headquarters was located," he said. "A huge number of those who were there died."

The claims could not be verified by Reuters and Russia's defense ministry was not immediately available for comment.

Moscow is also targeting Ukraine's energy infrastructure with waves of missile and drone strikes, at times cutting off electricity for millions of civilians in winter, when temperatures often fall below zero Celsius.

Russian forces used Iranian-made drones to hit two energy plants in the Black Sea port of Odesa on Saturday, knocking out power to about 1.5 million people - virtually all non-critical infrastructure in and around the port.

Zelenskiy said other areas experiencing "very difficult" conditions with power supplies included the capital Kyiv and Kyiv region and four regions in western Ukraine and Dnipropetrovsk region in the centre of the country.