LONDON (Reuters) - Prime Minister Theresa May unveiled details of her plan to protect the rights of EU nationals living in Britain on Monday, saying the government would work to offer them largely the same benefits as British citizens.

Britain's Prime Minister, Theresa May, leaves 10 Downing Street, in central London, Britain June 26, 2017. REUTERS/Stefan Wermuth

An agreement on the post-Brexit rights of EU nationals is one of the easier issues for the two sides to settle, with both Britain and the rest of the bloc wanting to provide assurances to millions of their citizens living abroad.

But the EU’s top negotiator Michel Barnier said Britain needed “more ambition, clarity and guarantees” in its position. “EU goal on citizens rights: same level of protection as in EU law,” he said in a tweet.

Reflecting the complexity of family relationships born of more than 40 years of EU membership, some lawmakers demanded clarity on what the changes meant for EU citizens’ family members and spouses from non-EU states.

And a major sticking point, which Brexit minister David Davis said at the weekend would be the row of the summer, was that Britain would not defer to rulings from the European Court of Justice - an institution the EU says must be involved.

“I want to completely reassure people that under these plans, no EU citizen currently in the UK lawfully will be asked to leave at the point the UK leaves the EU. We want you to stay,” she told a rowdy session of parliament, adding some detail to a proposal made to Brussels on Friday.

“I believe it is a generous offer.”

May made her pitch just hours after winning a deal to prop up her minority government with Northern Ireland’s Democratic Unionist Party, necessary to give her a better chance of passing laws to ease the path of Brexit during two years of talks.

But her authority is weakened and her strategy for Brexit is openly challenged both inside and outside her party, after she lost her parliamentary majority in an election she did not have to hold. The EU is determined to press home its advantage.

“MANDATE IN TATTERS”

Jeremy Corbyn, leader of Britain’s main opposition Labour Party, said May’s reduced stature after losing her majority in the June 8 election, meant that she could no longer wring out a good deal for Britain from the EU.

“She wanted a landslide and she lost her majority. Now her mandate is in tatters, but the prime minister still insists she’s the best person to get a good deal for Britain,” he said to loud cheers from his party.

“The truth is this country needs a new approach to Brexit.”

The 15-page document giving a point-by-point explanation of the proposals said Britain would allow current immigrants from the EU to retain healthcare, work rights and other benefits that are more generous than those given to migrants from elsewhere.

It said those who had lived in Britain for five years by an as yet unspecified cut-off point could acquire “settled status”, similar to permanent residency. Those more recently arrived would be allowed to stay until they achieved this status.

But “settled status would generally be lost if a person was absent from the UK for more than two years, unless they have strong ties here”, the government added.

Asked about how much it would cost EU citizens to establish their residency status in Britain, May’s spokesman said: “As a general principle (we) are looking to recover what is spent on the immigration system but we want the fee to be a very reasonable one.”

The government currently charges almost $3,000 per person to apply for permanent residence.

Monday’s presentation offered more details of a proposal May brought to an EU summit last week, an offer which European Council President Donald Tusk said fell short of expectations and could water down citizens’ rights.

Some commentators say May, who was once interior minister and in control of immigration policies, should have made her offer shortly after Britain voted to leave the European Union or at the latest after she triggered Article 50 of the EU treaty to start the process of leaving the bloc.

That, former government official and professor of Economics and Public Policy at King’s College London Jonathan Portes said, could have won her some goodwill in talks on a future trading relationship which could make or break thousands of businesses on both sides of the Channel.

The EU has said before tackling trade and their future relationship that there needs to be “significant progress” on EU priorities, including its demand that Britain settle a “Brexit bill” and the rights of expatriate citizens.

May’s spokesman was upbeat, saying the prime minister was confident of getting a good deal with the EU.

“It is the start of a negotiation,” he said, responding to criticism of the rights’ offer from the EU. “We believe we have made a fair offer.”