The European Union‘s Brexit negotiator Michel Barnier has said that negotiations on a future trading relationship with Britain would be “difficult and demanding”, as the bloc “will not tolerate unfair competitive advantage”.

“The UK should not think that zero tariffs, zero quotas will be enough,” he said in a speech on Tuesday during Europe’s largest tech event, the Web Summit, in Lisbon, adding that time would also be “extremely short” to negotiate a new partnership.

“I know this negotiation will be difficult and demanding,” he said, listing state aid, social and environmental rights and taxes as top priorities for the European Commission.

“Even when the [Brexit] deal is ratified it will not be the end of the story … We have to build a new partnership with the UK after they withdraw,” he said, reiterating his view that the risk of Britain’s chaotic departure without a divorce agreement still existed.