LUXEMBOURG (Reuters) - Britain’s Foreign Secretary Boris Johnson said it was time to begin “serious negotiations” on Brexit, hours before Prime Minister Theresa May visits Brussels in an attempt to unlock the stalled talks.

“We think in the UK that it is time to get on with these negotiations ... for us to start some serious conversations about the future and the new relationship, the deep and special partnership we hope to construct,” Johnson told reporters.

“I think we will work very much in the interests of both sides ... let’s put a tiger in the tank, let’s get these negotiations going and stop letting the grass grow under our feet. We hope very much that our friends and partners will take that message and really begin to do some serious negotiations.”

Johnson, arriving for talks in Luxembourg with his European Union peers on Monday, also said London made a “very good” and “fair” offer on safeguarding expatriates’ rights after Britain leaves the European Union.

May’s office said on Sunday she would meet the European Union’s chief Brexit negotiator Michel Barnier and the head of the bloc’s executive Commission, Jean-Claude Juncker, in Brussels on Monday.