The nearly 1,000 British nationals who work for the European Union's executive body have been assured their jobs are safe, even though Britain has voted to leave the European Union,

EU Commission President Jean-Claude Juncker wrote in an internal memo that according to regulations, they are "union officials" and work for Europe.

He wrote: "You left your national 'hats' at the door when you joined this institution and that door is not closing on you now."

The memo, distributed to Commission personnel after the results of Thursday's British referendum on EU membership became known, was obtained by The Associated Press on Monday.

Over the weekend, the resignation of the highest-ranking Briton at the Commission, Lord Jonathan Hill, was made public.

Hill's appointment as EU commissioner for financial services had been intended to serve as a bridge between the bloc and London's influential banking and financial services sector.

His resignation was accepted after Juncker's attempts to get him to change his mind failed, an EU official said Monday.

Hill, a former leader of Britain's House of Lords, "is a gentleman ... a solid member of team Juncker, particularly appreciated and liked," said Margaritis Schinas, Juncker's spokesman.

The resignation takes effect July 15. EU Commission Vice President Valdis Dombrovskis, in charge of the shared euro currency, will temporarily assume Hill's portfolio, but new candidates proposed by the British government for the EU Commission will be considered by Juncker, Schinas said.

As long as it officially remains part of the EU, Britain is entitled to a seat on the executive body led by Juncker, which currently has 28 commissioners, one per member country.

According to the British Permanent Representation to the EU, 980 British nationals work for the Commission, accounting for 4.2 percent of the total.

Britons are also employed by the EU's External Action Service, Council and Parliament.