The Minister for Foreign Affairs has accused Boris Johnson of "inflammatory language" and "spin" over his claims the EU is attempting to "blockade" goods travelling across the Irish Sea.
UK MPs will debate the Internal Markets Bill this week, which includes measures to override part of the Brexit withdrawal agreement.
The British government has admitted that the Bill breaks international law, with the EU Commission threatening legal action over what it considers a violation of an international treaty.
Simon Coveney said today that the plan has created "enormous tensions" in negotiations and has damaged the UK's reputation internationally.
Speaking on the BBC's Andrew Marr Show, Minister Coveney said the British Prime Minister's claim that the EU is threatening a customs border in the Irish Sea is a "bogus argument".
He said: "There is no blockade proposed and that is the type of inflammatory language coming from Number 10 which is spin and not the truth.
"What has been agreed is that there will be limited checks on goods coming from Great Britain to Northern Ireland because there is an agreement to prevent the need for physical border infrastructure on the island of Ireland.
"Therefore we have to ensure that goods are not travelling from Great Britain to the single market."
#Marr: Would the EU block goods entering Northern Ireland from Britain?
Irish Foreign Minister Simon Coveney: This "inflammatory language" coming from No 10 is "spin and not the truth"#Brexit https://t.co/bGfFiQ3VjM pic.twitter.com/zG3l0rKAvd
— BBC Politics (@BBCPolitics) September 13, 2020
Meanwhile, Justice Minister Helen McEntee said Mr Johnson's Brexit proposals have "damaged trust" and set back talks on a trade deal with the EU.
Minister McEntee told Sky's Sophy Ridge on Sunday that events this week have "certainly set us back".
She said the push from Mr Johnson to override parts of the Brexit deal he negotiated with Brussels last year has "damaged trust" between Britain and Ireland.
On the withdrawal deal, she said: "It was voted through the UK Parliament nine months ago, it was voted through the EU Parliament nine months ago, and now this week one side of the agreement essentially has decided to unilaterally change elements of that agreement.
"I think it has in some ways damaged trust between both sides.
"It's very difficult to see how you can negotiate a free trade agreement when what already has been agreed is proposed to be breached nine months later."
Johnson 'shaming' the UK
It comes after two former British Prime Ministers from different parties accused Mr Johnson of "shaming" the UK by proposing legislation which undermines his own Brexit deal.
Tony Blair and Sir John Major have written an article in the Sunday Times urging him to scrap the Bill.
They wrote: "We both opposed Brexit. We both accept it is now happening.
"But this way of negotiating, with reason cast aside in pursuit of ideology and cavalier bombast posing as serious diplomacy, is irresponsible, wrong in principle and dangerous in practice.
"It raises questions that go far beyond the impact on Ireland, the peace process and negotiations for a trade deal - crucial though they are. It questions the very integrity of our nation.
"As the world looks on aghast at the UK - the word of which was once accepted as inviolable - this government's action is shaming itself and embarrassing our nation."
Additional reporting by IRN