Theresa May will travel to Austria on Friday after Michel Barnier rejected the UK’s post-Brexit customs proposals.

The prime minister will meet with Chancellor Sebastian Kurz and the Czech prime minister Andrej Babis and attempt to gain support for her Chequers Brexit blueprint.

Barnier spoke at a joint press conference with Brexit minister Dominic Raab to warn against May’s Brexit plan.

“Maintaining control of our money, law and borders also applies to the EU’s customs policy,” he said.

“The EU cannot – and will not – delegate the application of its customs policy and rules, VAT and excise duty collection to a non-member, who would not be subject to the EU’s governance structures.”

“Any customs arrangement will also have to be workable and must protect EU and national revenue, without imposing additional costs on businesses and customs authorities,” he added.

Barnier also expressed concern over the UK’s proposals on a backstop agreement for the Irish border, where the UK hopes to avoid a hard border between Northern Ireland and the Republic of Ireland.

The UK has rejected the EU’s proposals on Ireland, saying that it will risk dividing Northern Ireland with the rest of the UK.

Raab said: “We have designed our proposals both to respect the result of the referendum, and the core principles of the EU. We have considered the innovative approaches the EU has taken in the past with other third countries – when the political will has been there.”

Whilst Raab also tried to claim the £39 billion divorce bill was conditional on future trade agreements, Barnier made clear that the sum of money had been “agreed for good”.

Barnier and Raab plan to meet again in mid-August and will then hold weekly discussions until October.