LONDON (Reuters) - Britain’s opposition Labour Party will immediately guarantee the rights of EU citizens living in the country if it wins a June election, it said on Tuesday, setting out a Brexit strategy aimed at eating into Prime Minister Theresa May’s runaway lead.

With May’s surprise decision to hold an early election on June 8 sending opposition parties scrambling to prepare in just six weeks, the Labour Party, which is around 20 points behind the Conservatives in the polls, will criticise what it calls May’s “reckless” approach to the divorce negotiations.

“EU nationals do not just contribute to our society: they are our society. And they should not be used as bargaining chips,” Labour’s Brexit spokesman Keir Starmer will say in a speech in London, according to advance excerpts.

“So on day one of a Labour government we will immediately guarantee that all EU nationals currently living in the UK will see no change in their legal status as a result of Brexit, and we will seek reciprocal rights for UK citizens in the EU.”

May has refused to calm concerns among EU citizens living in Britain over their future rights after Britain leaves the bloc, saying she would only give a commitment when she had won the same guarantees for Britons living in the European Union.

That has caused many to suggest she is using millions of EU citizens in Britain -- some who have lived in the country for years -- as bargaining chips in talks set to test even the most experienced negotiators with its complexity.

Starmer told BBC radio her stance was part of her “rigid” and “reckless ” strategy that was alienating EU negotiators before the talks have started in earnest and that Labour would set a more conciliatory tone to win a good deal which would include preferential access to the bloc’s single market.

“This is all about the tone and the approach, and the tone and the approach the prime minister has taken is to say ‘out out out’,” Starmer said.

“I am absolutely clear from my discussions in Brussels and elsewhere that (granting EU citizens’ rights) would be received as a very welcome message of the sort of approach the UK wants to take.”