Irish PM Varadkar in Brussels as Brexit talks enter frenzied fortnight

Ireland's Prime Minister Leo Varadkar arrives in Brussels to meet European Union officials on Thursday as Brexit talks enter a frenzied fortnight designed to produce a divorce deal with Britain and a blueprint for future ties.

The Brexit countdown begins with Varadkar meeting EU leaders' chairman Donald Tusk and the bloc's Brexit negotiator Michel Barnier later on Thursday.

Barnier will on Friday meet politicians from Northern Ireland where the Democratic Unionist Party (DUP), on which British Prime Minister Theresa May relies to govern, is key to sealing any agreement to end Britain's four decades in the bloc.

"It will be long hours and it may get messy but there will be a deal. The cost of no-deal is just too big," said a senior EU diplomat of the talks, aimed at agreeing a fix to the Irish border in time for an Oct.17-18 EU summit and then the outline of post-Brexit ties by another one on Nov.17-18.

Both sides are readying concessions and will exchange papers on the main potential deal-breaker - avoiding extensive border checks between EU-state Ireland and Britain's province of Northern Ireland after Brexit - as well as future ties.

If they fail to agree, Britain is bound to leave the bloc next March with little or no agreements in place to mitigate the economic shock and broad disruptions expected from air traffic to car production to food trade.

Should the leaders of the 27 EU states remaining in the bloc have no Brexit deal to sign off in November, they are due to move into contingency mode, stepping up preparations for a disorderly British departure.

Some diplomats and officials say talks could drag on through December, or even January, but any deal must also be ratified by both British and EU parliaments in time for Brexit day on March 29, 2019.