May called for closer ties with key ally Poland on Monday as part of an international charm offensive before the UK leaves the European Union.

"I am determined that Brexit will not weaken our relationship with Poland, rather it will serve as a catalyst to strengthen it," May said ahead of a meeting with Polish Prime Minister Beata Szydlo.

The two leaders were meeting in London to discuss defense, security and trade. Szydlo was also keen to examine increasing xenophobia in the UK following June's referendum.

Szydlo said Poland would be a "constructive partner" in negotiations with Brussels that set the terms for Britain's departure from the EU, but insisted Polish citizens in the UK not be held hostage.

"Whether we manage to complete this arduous task of bringing negotiations to a satisfying result will depend solely on our imagination and leadership," Szydlo wrote in an article for the Daily Telegraph newspaper. "We need a good compromise which gives both our countries the best possible options for economic and security cooperation ... But the initiative for determining British ambitions and expectations as to the future level of cooperation with the EU has to come from London."

Since joining the EU in 2004, Poland has been a close ally of Britain in calling for reform of the bloc. But June's shock decision to leave the EU sparked fear among 800,000 Polish people living in Britain as xenophobic attacks increased and their future was left in jeopardy.

"One thing is certain: millions of UK citizens living across the EU, and millions of EU-27 citizens living in the United Kingdom, should not be made to feel like hostages," Szydlo wrote. "That means we have to guarantee ... their right of residence."

Poland the most common foreign birthplace

May previously said she would preserve the rights of the 3 million EU citizens living in Britain following its divorce from Europe provided the more than 1 million Britons in Europe are afforded the same treatment.

"As we leave the EU, there will be a whole range of issues to address and settle, and clearly access to welfare systems will be one of those issues that needs to be looked at," a spokeswoman for May told reporters.

"I think what you do see from the prime minister and the Polish prime minister is a desire to provide reciprocity to British citizens and Polish citizens and other citizens in Europe," she said, adding that both sides were "keen to provide certainty for people."

Poland now represents the most common birthplace other than the UK for people living in Britain. May promised to rein in migration from the EU but said she remains committed to Europe.

In talks the two governments are expected to focus on defense policy, including the deployment of 150 British soldiers to north-eastern Poland, and foreign affairs such as Russia's activity in Ukraine and Syria.

aw/msh (AFP, Reuters)