Jeremy Corbyn has accused Boris Johnson of arrogance, after the Foreign Secretary said the European Union could "go whistle" if they make "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.
Mr Johnson's comments came after Number 10 sources played down suggestions that Theresa May plans to walk out of Brexit talks in September to show defiance over EU demands for a divorce bill worth tens of billions of pounds.
The Foreign Secretary said the public wanted the Government to "get on and deliver a great Brexit" and insisted that "there is no plan for no deal because we are going to get a great deal".
His comments were dismissed as absurd by Labour MP Chris Bryant, a leading member of the Open Britain campaign for continuing close links with the EU.
"Boris Johnson's bluster about getting a 'great deal' makes him sound like Donald Trump's unofficial spokesman, not the British Foreign Secretary," said Mr Bryant.
"Ministers have to drop this absurd threat of leaving with no deal, which would leave us worse off and for which the Foreign Secretary says they have done no preparation. Instead, they should negotiate a close relationship with Europe based on cooperation rather than confrontation."
But Mr Johnson's remarks were welcomed by Ukip Brexit spokesman Gerard Batten, who said the UK did not owe the EU "a penny".
"The EU will make excessive demands in all areas. They don't want us to leave and they will do all they can to delay, impede and discourage, in the hope we will change our minds," said Mr Batten.
"The Government should tell the EU to get lost. It should seize the initiative in the Brexit 'negotiations' and tell the EU how we are leaving – not ask it how."
Liberal Democrat Brexit spokesman Tom Brake said Mr Johnson's comments displayed "a shocking level of complacency".
"These kind of glib assurances are straight out of the Trump playbook," said Mr Brake.
"It is simply not good enough when people's jobs, living standards and rights are all on the line.
"People should be able to judge Boris Johnson on his actions not his words, with the chance to reject a disastrous Brexit deal and stay in the EU."
Asked if Mr Johnson was right to suggest there were no plans for leaving the EU without a deal, a Downing Street spokeswoman said: "Planning is under way across Government for all eventualities, which is what you would expect a responsible government to do."
On the question of payments to the EU, the spokeswoman said: "We have long said we are a country that will meet our legal obligations, whatever they may be."
She added: "Our view is that the days of us paying large sums of money to the European Union will be a thing of the past."