Poland, which borders Ukraine, risks becoming a future target of Russian attacks after Vladimir Putin invaded Ukraine on February 24.

The Sky Sabre system will help Poland defend its airspace from Russian weapons.

"As a NATO ally and a very old ally, Britain stands by Poland as Poland carries much of the burden of the consequences of this war," Wallace said after a meeting with Defence Minister Mariusz Blaszczak.

"We stand alongside Poland and protecting their air base from any further aggression by Russia", Wallace added.

Under the new agreement, Britain will help Poland develop the same missile defence system.

Britain has not revealed when the system will be deployed or for how long.

Sky Sabre has "the ability to hit a tennis ball at the speed of sound", Wallace said.