In Warsaw, Prime Minister Donald Tusk said the pact would be signed on Wednesday, calling it a "historic moment".

His UK counterpart, Keir Starmer, called it "the biggest step forward in our defence and security relationship with Poland in a generation".

The security and defence pact paves the way for joint military exercises and information-sharing, and will also cover cooperation in cyber and health security, according to the Polish government.

Starmer said it would allow both countries to "confront modern security threats that may be less visible but no less dangerous".

"Our collective work together will keep our countries safe for years to come," he added.

EU member state Poland shares its eastern border with Russia, Belarus and Ukraine.

But that geography means instability has become a reality for the former Warsaw Pact country, Tusk said.

"Certainly not for a month, but for years, given the neighbourhood," he added.

As a result, Poland's defence pacts with European countries, alongside its alliance with the United States, are designed to guarantee "total security", he added.

Poland, the most populous country on NATO's eastern flank, spends the most in the alliance on defence -- more than 4.8 percent of its gross domestic product this year alone.

At the beginning of May, Warsaw signed a loan agreement with the European Commission to finance the modernisation of its army and arms industry, under which it will receive nearly 44 billion euros.

Last year, Poland and France signed a treaty of friendship and enhanced cooperation, which includes defence and mutual assistance clauses that France, a nuclear power, reserves for its closest allies.