Poland will deliver an additional 60 tanks to Kyiv to help it fend off Russia's aggression, in a move hailed on Friday by Ukrainian President Volodymyr Zelensky.

"Thank you... Poland for these important decisions to deliver to Ukraine 60 Polish tanks -- 30 of which are the famous PT-91 Twardy, along with 14 Leopards," Zelensky said on Twitter.

Ukraine has also been promised battle tanks from Germany and the US, announced earlier this week.

Polish Prime Minister Mateusz Morawiecki revealed Warsaw's contribution in an interview with Canada's CTV News on Thursday.

"Right now, we are ready to send 60 of our modernised tanks, 30 of them PT-91. And on top of those tanks, 14 tanks, Leopard 2 tanks, from in our possession," he said.

He added that since the start of the war, Poland had "sent 250 tanks... or even more than that" to Ukraine.

The tanks that have already been sent by Poland are mainly T-72 Soviet models, of which the PT-91 are a modernised version.

After weeks of diplomatic wrangling, the US and Germany announced Wednesday the deliveries of their heavy Abrams and Leopard tanks to Ukraine, a step seen as a breakthrough in efforts to support war-torn Ukraine.

Berlin also authorised other countries to send their own Leopards to Kyiv.