Expectations grew ahead of the meeting at the Ramstein Air Base in Germany that Ukraine's Western allies would agree to send German-made Leopard tanks, amid mounting pressure from several European countries to do so.

But German Defence Minister Boris Pistorius told reporters on the sidelines of the event that "we still cannot say when a decision will be taken, and what the decision will be, when it comes to the Leopard tank".

He also denied accusations that Germany alone was blocking tank deliveries. The impression that "there is a united coalition and that Germany is standing in the way is wrong," he said.

Pistorius added that he has ordered a stock-take of Leopards so that action can follow quickly if the decision were to be positive for delivery.

Kyiv wants the powerful Leopard tanks to press offensives against Russian troops, but the Kremlin has warned their delivery by the West would amount to an "extremely dangerous" escalation.

Germany's hesitation so far on supplying the tanks has led to fierce criticism of Berlin from other countries such as Finland and Poland, which have their own stocks of Leopards but would need German approval to send them.

Zelensky on Friday renewed his plea for Western allies to "speed up" arms deliveries to Ukraine as he addressed the conference, which gathered representatives from 50 countries, via video-link.

Partners needed "not to bargain about different numbers of tanks but to open that principal supply that will stop evil", the Ukrainian leader said.

- 'Decisive moment' -

Make the meeting a "Ramstein of tanks", Zelensky said, calling for future gatherings to "go down in history as a Ramstein of F-16s and long-range missiles".

The meeting's host, US Secretary of Defense Lloyd Austin, urged allies to "dig even deeper" to support Ukraine with weaponry at a crucial time, noting that Russia is "running out of ammunition and suffering significant battle losses".

"This is a decisive moment for Ukraine. The Ukrainian people are watching us, the Kremlin is watching us, and history is watching us," Austin said.

The Kremlin responded by accusing the West of harbouring a "dramatic delusion" that Ukraine can win on the battlefield, adding that the conflict was "developing in an upward spiral."

In the run-up to the meeting Ramstein, Western allies have offered a flurry of new arms shipments.

Finland became the latest on Friday to announce a 400-million-euro ($433 million) military aid package, its largest to date, and including heavy artillery as well as munitions.

It comes after allies including the United States and Britain announced substantial new arms shipments on the eve of the Ramstein talks.

The Pentagon offered $2.5 billion worth of supplies for Ukrainian forces, including Bradley fighting vehicles, armoured personnel carriers, air defence systems, and tens of thousands of rockets and artillery rounds.

But it did not include the ATA long-range missiles sought by Ukraine.

The missiles, which can travel up to 300 kilometres (180 miles), could enable Ukraine to strike Russian supply routes and depots far behind the front lines that are not reachable with current HIMARS rocket systems.

- UN convoy reaches Soledar -

But Western partners also fear that Ukraine could use long-range weapons to hit deep inside Russian territory or Crimea -- a peninsula Moscow annexed in 2014 -- despite Kyiv promising it would not do so.

Almost a year into Russia's invasion of Ukraine, the most intense fighting in recent months has centred around the eastern Donetsk region.

In Kramatorsk, a city in the industrial district under Ukrainian control, AFP journalists saw the aftermath of a Russian strike on a two-story school building.

The attack had carved a huge crater in front of the kindergarten, which had some 250 pupils and 70 staff before the war broke out.

Debris from the strike, which sparked a small fire and smashed windows, was strewn around the playground and lay near colourful murals on a school building.

"It's hard to see the building like this, thinking about how much money and time it's going to take to return it to what it was," the kindergarten's deputy director Margarita Oleksandrivna told AFP.

About 60 kilometres from Kramatorsk, in Soledar, the first humanitarian convoy of the UN finally arrived in the town that has been largely reduced to rubble by intense fighting.

"Recent fighting in and around Soledar has caused widespread destruction, leaving people there in dire need of humanitarian assistance," said Jens Laerke, a spokesman for the UN humanitarian agency OCHA.

Russia claims to have seized Soledar, but Ukraine insists the fighting, in which both sides have suffered heavy losses, is ongoing.

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