Boris Johnson has said the sums of money the EU is proposing to demand from Britain for Brexit "seem to be extortionate".
The Foreign Secretary was asked in the Commons whether Brussels should be told to "go whistle" if it asks for a hefty sum from Britain in the form of a so-called "exit bill" for leaving the European Union.
He said: "I think that the sums that I have seen ... seem to me to be extortionate and I think go whistle is an entirely appropriate expression."
Labour leader Jeremy Corbyn accused Mr Johnson of being "arrogant" and said the "silly remarks" were counter-productive.
"Go whistle" is a phrase that means asking for something with little chance of getting it.
European Commission President Jean-Claude Juncker has suggested the final bill, which covers outstanding liabilities for programmes the UK signed up to as an EU member and ongoing costs for things like staff pensions, could be around £50bn.
Unconfirmed reports have claimed the final figure could be almost twice that amount.
Mr Johnson also claimed the Government has not made any plans for a "no deal" Brexit because the UK will get a "great deal" in the negotiations and the chances of there not being an agreement are "vanishingly thin".
This contradicts Brexit Secretary David Davis, who said in June: "We have worked up that alternative in some detail. We are still working on it."
The Prime Minister's spokeswoman later slapped down the Foreign Secretary, saying Britain was "planning for all eventualities".
Answering questions on Brexit from peers after Mr Johnson's appearance in the Commons, Mr Davis laughed off his Cabinet colleague's comments.
He said the British strategy on the "exit bill" was "not to pay more than we need to" and the Government would not accept the EU's "first claim" without going through it in detail.
"There will be a process of challenge going on here - and that will happen and has started already in the negotiated process to establish whether or not we believe in that particular case they have made a legally defensible argument or not," Mr Davis said.
Asked about Mr Johnson's comments, the Brexit Secretary laughed before saying: "Bluntly, I wouldn't worry. I mean you will have to get the Foreign Secretary here to explain his views if you really wanted to. I'm not going to comment on other ministers."
Mr Davis told the European Union select committee that all of the British newspapers are read in Brussels and they "take them, if anything, too seriously".
"More importantly in the context of the 27, actually very little of what happens here percolates across."
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?"
He said Labour would "pay what we are legally required to pay", but nothing beyond that.
Liberal Democrat Brexit spokesman Tom Brake said Mr Johnson's remarks displayed "a shocking level of complacency".
"These kind of glib assurances are straight out of the Trump playbook," he said.
"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."