The EU’s Brexit negotiator has said he sees the process as an opportunity to “teach the British people and others what leaving the EU means”.
Michel Barnier said he would never resort to blackmail but saw it as his job to “educate” the UK about the price it would pay for leaving the EU “club”.
The UK has hit back, saying the EU does “not want to talk about the future”.
Brexit Secretary David Davis said it was “frightened” and the UK would not be bounced into a divorce bill deal.
The latest salvos come after a week of talks in Brussels about the UK’s withdrawal from the EU – scheduled to take place in March 2019 – which increased tensions between the two sides.
Mr Barnier accused the UK of “nostalgia” and cast doubt on whether enough progress had been made to broaden the discussions, in the autumn, to consider the UK’s post-Brexit trading relationship with the EU.
This led to a frosty response from British ministers, one of whom, International Trade Secretary Liam Fox, said the UK would not be blackmailed into doing a deal on money in order to open discussions on trade.
Speaking at a conference in Italy on Saturday, Mr Barnier said he did not want to punish the UK for leaving but said Brexit would be “an educational process” for the British.
On the issue of finance, he said the UK must accept some key principles, such as honouring the commitment it made in 2014 to pay 14% of the EU budget until 2020
He said that a future free trade deal would be different to all others in the past and there had to be assurances there would be no unfair competition in the form of social, environmental or fiscal dumping, or state aid.
The UK was assessing the EU’s financial demands on an item-by-item basis in a “very British and pragmatic fashion” – which he said the EU found difficult.