Sammy Wilson has accused the Government of conceding to the EU over whether its officials will be required to monitor goods coming into Northern Ireland from Britain.
The DUP MP was speaking after asking Cabinet Minister Michael Gove in the Commons about the EU's position on checking goods entering here.
Mr Gove told MPs that "we want to have a pragmatic approach whereby the UK is responsible for the administration of these controls, but we want to provide the EU with reassurance wherever possible".
Mr Wilson said later: "On the face of it, the Government appear to be standing up to Brussels.
"Yet, as Michael Gove's answers today reveal, this brave face could be cover for an eventual climbdown and acceptance of Brussels' more outrageous demands.
"This seems to be the case as far as Northern Ireland is concerned. The Government appears to have conceded that checks on goods coming into Northern Ireland will not be conducted solely by UK officials, but will also require an EU presence at the internal UK border between Northern Ireland and GB."
He added that Mr Gove's response "was classically evasive and can only be interpreted as the Government giving into the EU demand when, two months ago, he told an audience in Belfast that under no circumstances would there be an EU presence in Northern Ireland".
"The pattern appears to be talk tough and then give in to the EU. The question is, on how many other occasions can the Government get away with it?"
SDLP MP Claire Hanna said: "We've 70 days to go here and businesses deep in the middle of a pandemic are trying their best to prepare, but there are so many unanswered questions which all add up to costs Northern Ireland can't afford.
"Firms and families here desperately want a deal but all we are hearing is the blame game and brinkmanship and deflection and jingoism. People in Northern Ireland are more anxious than they have been in decades, with absolutely no sense that this Government understands that.
"Can I ask (Mr Gove) is there any upper limit to the damage he thinks Northern Ireland should have to sustain for a Brexit that we've rejected at every possible opportunity?"
Mr Gove responded: "We've made significant progress today in the joint committee thanks to the constructive approach taken by vice president Maros Sefcovic. We're lucky that vice president Sefcovic and his team are so committed to making sure that the protocol works."
Labour warned Boris Johnson is pursuing a "Narnia deal" with the EU, as they urged the UK Government to secure a trade agreement.
Shadow cabinet office minister Rachel Reeves said: "They can call it no deal, they can call it an Australia deal, they can call it a Narnia deal as far as I'm concerned, but let's be honest about what that means - and let's be honest about how damaging it is for the country."
After a Tory MP shouted "it's not damaging", Ms Reeves countered: "10% tariffs on British cars being exported to the EU - that is damage. 40% tariffs on lamb being exported to the EU - that is damage."