The UK Prime Minister Theresa May tried to reassure EU leaders over Brexit when she attended her first European Union summit on Thursday in Brussels, but she was told by French President Francois Hollande to prepare for tough negotiations.

May has said she will formally notify the EU of Britain's plan to leave by the end of March, but she and her ministers have sent conflicting signals about what kind of relationship that the UK wants with the EU once the divorce talks end.

In early October she suggested that she was leaning towards a so-called "hard Brexit", in which Britain would place limits on immigration and lose access to Europe's lucrative single market.

During the summit, leaders from the bloc made clear that they would not bow to May's suggestion that preparatory talks take place before she invokes Article 50 of the EU treaty, starting the two-year countdown to Brexit.

On Friday, sterling edged down against the dollar, hurt by expectations that Britain's economy is likely to suffer from the leave negotiation with the EU members.