Pro-EU demonstrators protest outside parliament in Westminster London, Britain, September 13, 2018. REUTERS/Henry Nicholls

BRUSSELS (Reuters) - European Union leaders will discuss when they meet in Austria next week whether to hold a special summit on Brexit in November, a senior EU diplomat said on Thursday.

He also said, when asked by reporters, that the EU was continuing contingency preparations in the event there is no deal before Britain leaves next March.

Diplomats and EU officials say that governments have been discussing holding a special Brexit summit in Brussels around Nov. 13-15 on the assumption that a regular meeting on Oct. 18 will be too early to approve a potential deal with Britain on a withdrawal treaty.

The diplomat, briefing reporters, said further discussion on a November meeting would take place among heads of state and government when they meet in Salzburg next Wednesday and Thursday.

Asked whether the Salzburg summit would give EU negotiator Michel Barnier a new mandate to discuss terms for Britain’s future trade relationship with the Union, the diplomat said Barnier did not need such a formal mandate. He might, however, seek further guidance from leaders during the meeting.

He was asked about comments from British Brexit Secretary Dominic Raab that a failure to reach a deal on the withdrawal treaty would mean Britain not paying tens of billions of euros it has so far agreed to send to Brussels.

He said that if there were no treaty, many of the agreed terms would lapse. However, he said, there was a legal argument that Britain would still owe money to the EU under the terms of its existing membership obligations.