Paweł Soloch, national-security aide to the Polish President Andrzej Duda, delivered the news at a media briefing, the state PAP news agency reported.
The official noted that Duda had recently hosted two-day security talks with his Ukrainian counterpart Volodymyr Zelensky, in the southern Polish resort town of Wisła.
“In the meantime, the president held a series of meetings with government officials, ministers, security services chiefs, and spoke directly to Prime Minister Mateusz Morawiecki,” Soloch said.
“Last Friday, we had a meeting of the National Security Council, which sent a strong, cross-party message (...) about the shared position of the Polish elites regarding the situation in Ukraine,” he added.
Soloch emphasised that all of Duda’s talks focused on support for Ukraine.
“By this we mean political support, but also material assistance, both in the humanitarian and military sense,” the aide told reporters.
“A decision has been made to provide Ukraine with defensive ammunition, which is to be used in defence, not attack,” Soloch stressed, adding that the move was decided “in close contact with the president” and would be finalised by Defence Minister Mariusz Błaszczak.
The aide said Poland’s offer comprised tens of thousands of defensive-ammunition units, ready to be supplied “at any moment,” PAP reported.
On Tuesday, PM Morawiecki will pay a visit to Ukraine, having warned on Sunday against “Russian neo-imperialism” and declared Warsaw’s “unwavering support” for Kyiv.
Russia's deployment of troops near Ukraine has raised fears in the West that Moscow, which seized Ukraine's Crimea peninsula in 2014 and has since backed separatists fighting in eastern Ukraine, may be poised for a new attack, the Reuters news agency has reported.
Russia has denied plans for an assault but says it could take unspecified military action if its security demands, including a ban on NATO expansion, are not met, according to Reuters.