EU ambassador warns a trade deal must be finished by October to avoid a hard Brexit

The EU ambassador to the UK has warned that Britain faces crashing out of the single market if it does not reach a deal with Brussels by October.

Ambassador Joao Vale de Almeida stressed that the two sides were in a 'unique and historic' situation during a Chatham House debate on the future of the EU-UK relationship.

'The United Kingdom has confirmed that they don't want to extend the transition period. We took note,' he said.

'If you do a count down and if you count the need for ratification time, it means that we need to have a deal by, let's say, the end of October, which is in exactly four months.'

He added: 'We were open for that, but we respect the United Kingdom position.'

Boris Johnson has repeatedly ruled out prolonging negotiations, warning that Britain would walk away from talks if the EU did not cede to UK demands on the level playing field and fisheries. Downing Street have now said that a deal is possible by July.

Probed on whether an outline of a deal could be reached within the prime minister's ambitious new timeline, Vale de Almeida said: 'I think that speed is good. We need to accelerate.

'We need to use every week and every month to try to find a deal.

'But when you drive a car and you speed too much, you can risk falling out of the road, so you need to be careful.'

The ambassador said a so-called 'skinny deal' being proposed by the UK could be more difficult to agree and ratify than a comprehensive agreement.

'Sometimes skinny deals are more difficult to negotiate than larger deals,' he remarked.

'In a more comprehensive deal you can find better trade offs, you can accommodate different interests.'