Javier Pinanes, director of Spain's tourist office in London, said hotels in destinations like the Balearic Islands are heavily reliant on the millions of tourists who visit from the UK every year.
And he acknowledged travel disruption which could follow if the UK leaves the EU without a deal would be "a really big problem".
His warning comes as negotiators from the UK and EU attempt to reach a compromise over the Irish border as exit talks enter their final crucial stages.
Yesterday, Brexit Secretary Dominic Raab told MPs an agreement is within sight but said the Government is also “expediting preparations” for a potential no deal. Express.