BRUSSELS, March 19 (Xinhua) -- The European Union (EU) and Britain on Monday reached a Brexit transition deal, which is expected to be signed off by leaders during Friday's EU Summit.

"A good deal for the EU and Britain is closer than ever before," said Britain's Brexit Secretary David Davis during a joint press conference with his EU counterpart Michel Barnier.

However, "the transitional period will only come after everything is agreed," said Barnier, EU's chief Brexit negotiator.

Hailing the deal as a "decisive step", Barnier and Davis said they had agreed on a "large part" of terms for a transitional deal but issues still need to be resolved including the Northern Ireland border.

Britain agreed to a contentious "backstop solution" which would keep Northern Ireland signed up to EU rules in order to avoid a hard border with the Republic of Ireland, said the deal.

EU27 citizens arrive in Britain during transitional period will have same rights with citizens arriving before the Brexit, said the deal.

Britain will stay in the single market and customs union for 20 months after it leaves the EU in March 2019 and will be able to sign new free trade deals during the transition -- but they won't come into effect until after the period has ended, said the deal.

Meanwhile, any agreement reached at the summit this week will be a political commitment -- not legally binding until the final withdrawal agreement is signed early next year, according to some local media reports.

British Prime Minister Theresa May sent a notification letter to the EU in late March last year, triggering a two-year countdown to Britain's withdrawal of the bloc after more than 44 years of membership.