Britain must pay a divorce bill of 'around' £50billion to get a 'friendly' deal with theEU, Jean-Claude Juncker has warned.

The European Commission president insisted Theresa May would be made to 'honour' the UK's commitments when Brexit negotiations get under way next week.

The tough line will increase tensions ahead of the Prime Minister formally triggering the Article 50 process on Wednesday.

The demand for a huge settlement to be agreed before talks on trade get going is shaping up to be a major roadblock.

European Commission President Jean-Claude Juncker (PA)

Ministers have indicated they will not tolerate any sum above around £3billion, and Mrs May has said she is ready to walk away from the table if the EU does not offer reasonable terms.

Mr Juncker told the BBC that Brussels did not want to 'punish' the UK for leaving, describing Brexit as 'a failure and a tragedy'.

He promised that Brussels will approach the negotiation of Britain's withdrawal in a 'friendly' and fair way.

But Mr Juncker also warned that European institutions were not 'naive' about the process - and confirmed a divorce bill of around £50billion will be presented early in the process.

'It is around that,' said Mr Juncker. 'We have to calculate scientifically what the British commitments were and then the bill has to be paid.'

The liabilities identified by the EU include projects the UK has agreed to help fund - even though we will not now get the benefits - as well as pensions for Eurocrats.

'You cannot pretend you were never a member of the union,' Mr Juncker said.

'The British government and parliament took on certain commitments as EU members and they must be honoured. This isn't a punishment or sanctions against the UK.'

Theresa May, pictured in the House of Commons yesterday, has said she is ready to walk away from negotiations if the EU does not offer reasonable terms

Mrs May will formally notify Brussels of Britain's intention to leave the EU in a letter to the European Council on March 29 – just four days after the EU's 60th anniversary celebrations in Rome on Saturday.

That will begin a two-year process of negotiation with Brexit schedule to happen by March 29 2019.

Asked how he felt about Brexit, Mr Juncker said: 'It is a failure and a tragedy.

BEMUSED JUNCKER INSISTS PM IS 'NOT AN ELEPHANT' Jean-Claude Juncker appeared confused when he was asked whether Theresa May would be the 'elephant in the room' during the BBC interview. The EU commission chief, who speaks four languages fluently, was discussing the bloc's 60th anniversary celebrations in Rome this week when the question was posed. The PM is not attending to avoid aggravating tensions with the 27 states. But Mr Juncker did not seem to recognise the idiom. The puzzled Eurocrat replied: 'She's not an elephant.' He added later: 'Of course we will miss her.' Advertisement

'I will be sad, as I was sad when the vote in the referendum took place in Britain. For me, it is a tragedy.

Mr Juncker was asked whether he will miss Theresa May at the EU 'birthday' summit tomorrow to mark the 60th anniversary of the Treaty of Rome.

The PM is not attending to avoid aggravating tensions with the 27 states.

'Of course we will miss her,' Mr Juncker said.

'I am everything but in a hostile mood with Britain. Britain is part of Europe, and I hope to have a friendly relationship with the UK over the next decades.

'We will negotiate in a friendly way, a fair way, and we are not naive.'

Mr Juncker made clear he wanted an early deal to protect the status of some three million EU nationals resident in the UK, and one million Britons living on the continent.

'I am strongly committed to preserving the rights of Europeans living in Britain and British people living on the European continent,' he said.

'This is not about bargaining, this is about respecting human dignity.'