Theresa May to brief EU leaders on plans to offer certainty to EU nationals living in UK after Brexit
Theresa May is set to make her offer over the status of expat citizens following Brexit to her European counterparts at a summit in Brussels.
Ahead of the European Council summit, the prime minister said she was "very pleased" to be there following a "constructive" start to negotiations at the start of the week.
Mrs May said: "Today, I going to be setting out some of the UK's plans particularly on how we propose to protect the rights of EU citizens and UK citizens as we leave the European Union."
"That's been an important issue. We've wanted it to be one of the early issues to be considered in the negotiations. That is now the case, that work is starting," she added.
There are an estimated 3.2 million EU nationals in the UK and 1.2 million UK citizens in the EU.
Full details of the UK proposals will be published on Monday.
The prime minister also said other "important issues" such as counter-terrorism will be on the agenda.
"One of the things I will be calling on with other European leaders today is that we do more working together, to ensure that we stop the spread of extremism online," she said.
The two-day summit is the first time since the election that Mrs May has met other EU leaders.
Earlier, Foreign Secretary Boris Johnson said he hoped leaders of the 27 other nations would match Mrs May's "generous" proposals with similar offers to the one million British expats on the continent.
The 27 remaining members will also hear a report from chief negotiator Michel Barnier on his talks with David Davis earlier this week.
The Brexit Secretary accepted a European timetable to put off talks on a future trade relationship until progress has been made on the terms of the divorce.
Downing Street declined to reveal details of the proposals on citizens' rights but Mr Johnson said: "I think she's got a great offer to make and I hope it will go down well."
In a two-day summit whose agenda is formally dominated by immigration, security and the economy, Mrs May will also brief her counterparts on the UK's commitment to a new £75 million plan designed to stem the flow of illegal migrants from Africa to Europe.
The three-year programme will offer humanitarian support, including food and water, to would-be migrants on the perilous transit routes from the Horn of Africa and western Africa through countries including Niger, Egypt and Libya.
Migrants who find themselves stranded and destitute along the routes will be offered assistance to return home.
Also on the agenda in Brussels will be counter-terrorism co-operation, sanctions on Russia and Europe's response to the US withdrawal from the Paris Accord on climate change.
Mrs May is expected to urge member states to follow the lead of a UK-French agreement to put pressure on internet companies to remove extremist material from their sites, sealed with President Emmanuel Macron on a visit to Paris last week.
Mr Macron and Irish Taoiseach Leo Varadkar - who met the PM at Downing Street on Monday - will be making their first appearances at a European Council summit following their election victories.