Salzburg, Austria  - EU leaders are to turn their attention to Brexit on Thursday, the second day of an informal meeting in the Austrian city of Salzburg, after British Prime Minister Theresa May briefed them on her view of negotiations.

Over dinner on Wednesday, May told her European Union colleagues that the onus was now on Brussels to find common ground as the clock ticks down to reach a deal on Britain's departure from the bloc on March 29, 2019.

May has been touting her "Chequers Plan," which she called on Wednesday "the only credible and negotiable plan on the table." EU leaders are trying to decide how much flexibility to offer May so that she has a stronger hand at home. May will not be present Thursday, when the discussions will include the EU's Brexit negotiator Michel Barnier.

EU leaders will also consider whether a special summit will be needed in November. European Council President Donald Tusk warned Tuesday a no-deal Brexit was "still quite possible" and suggested an extra meeting might be necessary.

Key questions remain for negotiators, including the issue of the Irish border. Without a deal, EU rules would cease to apply in Britain overnight, likely leading to chaos.

Another topic to be taken up Thursday is a European Commission proposal to build up Frontex, the European Border and Coast Guard Agency, from 1,500 to 10,000 employees by 2020 and give it further powers.

While there is support in principle, there are concerns about whether expanding its mandate would interfere with national and local authorities.