Ukrainian President Volodymyr Zelensky is visiting Poland, buoyed by the latest announcement of United States military aid, as Russian troops press on with their long and costly battle to seize the eastern city of Bakhmut.

Mr Zelensky planned to thank his Polish allies, who have provided vital weaponry to his government since Russia’s invasion and have taken in millions of Ukrainian refugees.

French President Emmanuel Macron, meanwhile, was visiting China after he and US President Joe Biden agreed they would try to engage Beijing to hasten the end of the Russian assault on Ukraine, now in its second year.

Beijing has called for a comprehensive ceasefire and described its position on the conflict as “impartial”.

Aid boost

The US on Tuesday pledged $US2.6 billion ($3.9 billion) more in military assistance for Mr Zelensky’s government, including three air surveillance radars, anti-tank rockets and fuel trucks, taking pledged US military aid to more than $US35 billion ($52 billion).

Moscow’s embassy in Washington accused the US of wanting to drag out the conflict as long as possible, Russian news agency TASS said.

The West has stepped up aid as Ukrainian forces prepare to mount a counteroffensive in the east against Russian forces, although when exactly it might kick off has not been disclosed.

Spain said six Leopard 2A4 tanks it has promised to send to Ukraine would leave the country in the second half of April, later than initially planned.

Spain has also trained 40 tank crew members and 15 mechanics at a military base in the north-eastern city of Zaragoza.

Other NATO countries, including Germany, Poland and Portugal, have promised to send a total of 48 Leopard 2 tanks to Ukraine.

The battlefield focus remained on Bakhmut, a mining city and transport hub on the edge of a chunk of Donetsk province largely under Russian control.

Both sides have suffered huge casualties and much of the city has been reduced to ruins after months of street fighting and bombardments.

Ukrainian military commanders have stressed the importance of holding Bakhmut and other towns and inflicting losses prior to the anticipated counteroffensive.

The Ukrainian general staff said in a report: “There was no letup in enemy actions aimed at storming the city of Bakhmut. At least 20 enemy attacks were repelled here alone over the past 24 hours.”

Mercenaries from the Wagner group, which has spearheaded the assault on Bakhmut, said at the weekend they had captured the city centre, a claim dismissed by Kyiv.

The US-based Institute for the Study of War said the Wagner fighters had made advances in Bakhmut and were likely to continue trying to consolidate control of the city centre and push westward through dense urban areas.

Reuters could not verify the battlefield reports.

In Warsaw, Mr Zelensky was due to meet President Andrzej Duda and Prime Minister Mateusz Morawiecki and speak to Ukrainian refugees.

The Ukrainian leader crossed the border into Poland, which has played an important role in persuading other Western powers to supply battle tanks and other weaponry to Ukraine, on Wednesday morning.

“It will not be a surprise to anyone that the Ukrainian side will ask Poland and other foreign partners for more support … but we must be aware that we as Poland have already really done a lot,” Polish presidential aide Marcin Przydacz said.

Mr Przydacz said earlier a first shipment of MiG fighter jets had already been delivered to Ukraine.

“MiGs from Poland will significantly strengthen our defence, allow us to make our skies safer, save the lives of our citizens and also reduce the destruction caused by Russian attacks,” Ukrainian Defence Minister Oleksii Reznikov wrote on Telegram.

Mr Macron, speaking on arrival in Beijing, said China could play a role in resolving the Ukraine war because of Beijing’s tight relationship with Russia.

He and European Union executive head Ursula von der Leyen are seeking to “reset” ties with an important economic partner while broaching thorny issues like Ukraine and trade risks.