One of the European Union's top politicians has warned the UK against delaying Brexit negotiations and risking leaving without a deal in place as a result.

The president of the European Council - which brings together heads of state to set the political agenda for the bloc - tweeted this morning using the handle @eucopresident: "We don't know when Brexit talks start. We know when they must end. Do your best to avoid a 'no deal' as result of 'no negotiations'. #GE2017".