Labour leader Jeremy Corbyn has accused Boris Johnson of arrogance, after the British Foreign Secretary said the European Union could "go whistle" if it makes "extortionate" demands over Brexit.
Mr Johnson was responding in the House of Commons to questions over the proposed "divorce bill" which the UK is expected to receive next week as Brexit negotiations resume in Brussels.
European Commission president Jean-Claude Juncker has suggested that the bill, which covers outstanding liabilities for programmes which the UK signed up to as an EU member, as well as ongoing costs including staff pensions, could be around £50 billion, while unconfirmed reports have claimed it could reach almost twice that figure.
Addressing Mr Johnson at foreign affairs questions in the Commons, Tory eurosceptic Philip Hollobone said the UK had made a net contribution of £209 billion to the EU since joining in 1973, adding: "Will you make it clear to the EU that if they want a penny piece more then they can go whistle?"
Mr Johnson replied: "I'm sure that your words will have broken like a thunderclap over Brussels and they will pay attention to what you have said.
"He makes a very valid point and I think that the sums that I have seen that they propose to demand from this country seem to me to be extortionate and I think 'to go whistle' is an entirely appropriate expression."
Speaking outside the Commons chamber, Mr Corbyn said: "I think it is ridiculous for the Foreign Secretary to approach important and serious negotiations with that silly, arrogant language that he so often employs.
"Treat people with respect and there's a fair chance you will be treated with respect in return.
"If you start on the basis of those silly remarks, what kind of response does he expect to get?"
Mr Corbyn is due to meet the EU's chief Brexit negotiator Michel Barnier in Brussels on Thursday, to set out his party's approach to Brexit and hold "exploratory discussions" about the negotiations ahead.
He said Labour would "pay what we are legally required to pay", but nothing beyond that.
"We have to negotiate intelligently and sensibly, but above all negotiate with respect and expect to be respected in return," said Mr Corbyn.
The UK's negotiating team under Brexit Secretary David Davis is due to begin the first full round of negotiations with Mr Barnier on Monday.
May says determination to change Britain 'undimmed'
British Prime Minister Theresa May has insisted that her determination to change Britain in the interests of those who are "just about managing" remains "undimmed" despite the loss of her parliamentary majority.
In her first major speech since the general election last month, Mrs May said she would act to protect the rights of workers.
Theresa May says her government is determined to 'take the bold action necessary to secure a better future for Britain' pic.twitter.com/40qq0RmdOY— RTÉ News (@rtenews) July 11, 2017
And she appealed to other political parties to put forward their proposals for debate and discussion ahead of the government's full response to the report later in the year.
Mrs May acknowledged that the election result - which left her at the head of a minority government dependent on the support of the Democratic Unionist Party - was "not what I wanted".
However, she insisted that she would press forward with the reform agenda she set out when she first arrived in 10 Downing Street a year ago, saying: "My commitment to changing Britain is undimmed."
The Prime Minister added: "At this critical time in our history, we can either be timid or we can be bold."
"We can play it safe or we can strike out with renewed courage and vigour, making the case for our ideas and values and challenging our opponents to contribute, not just criticise.
"I think this country needs a government that is prepared to take the bold action necessary to secure a better future for Britain and we are determined to be that government.
"In everything we do, we will act with an unshakable sense of purpose to build the better, fairer Britain which we all want to see."