A member of the DUP has indicated his party could have supported an amendment to the UK’s flagship Brexit legislation guaranteeing the rights of people in Gibraltar.
Ian Paisley also urged ministers to confirm their assurances meant Gibraltar "will not be treated anyway differently than any other part of the United Kingdom".
The pro-Brexit DUP give the Tories a majority in the British House of Commons through their confidence and supply arrangement with the British Government.
British Brexit minister Steve Baker said the Government was "steadfastly committed to the interests of Gibraltar".
New clause 56 to the European Union (Withdrawal) Bill, tabled by SNP MP Peter Grant, aims to ensure the Bill does not remove or prejudice rights in Gibraltar after Brexit.
North Antrim MP Mr Paisley said: "This is the one amendment that actually would have attracted, probably, support from this bench, and it’s because of the assurances the minister has given, and importantly the assurances that the Prime Minister gave even today at the despatch box, that we feel very relieved for Gibraltar’s sake.
"Is he essentially saying that the protections that he is now affording to Gibraltar effectively means that it will not be treated anyway differently than any other part of the United Kingdom?"
Mr Baker told British MPs both the UK and the EU were clear Gibraltar was subject to the withdrawal agreement and the Bill only extended specifically to Gibraltar in one minor way.
He added: "I understand, though, the concerns being expressed through this amendment.
"In response to those concerns, I hope I can reassure that access to the UK market for Gibraltar is already protected by law, and it is the unshakeable objective of the UK Government to ensure the seamless continuation of existing market access into the UK and enhance it where possible."
Mr Grant’s amendment has gained support from a cross-party group of MPs, including a number of Conservatives.
The SNP’s Europe spokesman told Mr Baker: "I’ve no doubt that the people in government in Gibraltar will be grateful for his assurances.
"But for absolute clarity, the wording of this amendment intends to make sure with 100% certainty that even inadvertently, nothing in the Bill can damage the interests of the people of Gibraltar.
"Can the minister tell us with absolute certainty that if this amendment is not put into the Bill, that there’s nothing in the Bill that will cause that damage.
"Objectives are good, assurances are good, promises are good. Can he say with absolute certainty that nothing in the Bill will ever damage or prejudice the interests of the people of Gibraltar?"
Mr Baker replied: "What I can say to him is that this Bill only extends to Gibraltar in the way which I have set out.
"The Government’s policy is as I have indicated to him, and we remain steadfastly committed to the interests of Gibraltar."