"Europe will be safe as long as the skies over it are safe," Poland's Prime Minister Donald Tusk and Greek counterpart Kyriakos Mitsotakis wrote in a letter to EU chief Ursula Von der Leyen.

"That is why the EU needs a new flagship programme -- a European air defence shield -- a comprehensive air defence system to protect our common EU airspace against all incoming threats."

The proposal comes as EU nations scramble to bolster their defences and re-arm in the wake of Moscow's 2022 invasion of Ukraine.

Von der Leyen made reference to it in a debate Thursday against rivals competing with her as she seeks a second mandate.

She urged the next commission to pursue common European defence projects -- "for example, an air defence shield for all".

Poland and Romania, two EU countries bordering Ukraine, have already seen drones and missiles from the conflict cross into their territory.

"The European air defence shield must be a programme which addresses this major vulnerability in our security," the letter said.

"A programme which strengthens the EU's overall defence capabilities and incentivises European defence companies to develop cutting-edge technologies."

The scarcity of air defences in the EU has been underscored recently by the failure of countries beyond Germany to send more systems to Ukraine as it faces fierce bombardments from Russia.

Germany last year launched it own initiative along with NATO allies seeking to bolster the continent's air defences through joint purchases of equipment.

But that has failed to gain traction with key players such as France who objected to plans to buy the weaponry outside the EU.

Tusk and Mitsotakis said they looked forward to discussing their proposal with other EU leaders at a summit next month.