Sources have suggested that the Rock are exploring a variety of options through a formula which is currently being drawn up whilst ensuring relations between Spain and the UK are maintained. Gibraltar has been a continuing source of friction for Spain and the UK since it was ceded in Britain in 1713.
It is now a British Overseas Territory with the majority of its residents overwhelmingly voting to remain in the EU at the 2016 Brexit referendum.
It currently has a seat in the ongoing negotiations between the UK and the bloc.
Sources have suggested to Spanish Newspaper El Pais that one of the options on the table would be the Rock joining the EU Customs Union or the Schengen passport-free area.
He added: “This possibility cannot be ruled out”.
The sources suggested that Westminster should not raise concerns about the prospect following a suggestion that there could be a border in the Irish Sea.
They added: “Northern Ireland is part of the UK, but Gibraltar is a separate jurisdiction; there would be no broken unity.”
The territory’s future relationship with the EU also depends on talks between the UK and Spain, the sources suggested, which are “advancing in a constructive way.”
They stressed that the priority was “maintaining the welfare and prosperity” of the people who live in the area.
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“The issues are narrower as we progress to 31 December and all the work carried out so far is expected to be very useful if there is no agreement.”
However, he stressed that the Government remained confident that a good economic partnership could be agreed which would “greatly benefit” Gibraltar by enabling “an area of shared prosperity”.
Albert Isola, the British territory’s financial services minister had said that Gibraltar’s finance sector will likely be locked out of the European Union but logjams at the Spanish border would be far more of a blow to the economy.
He added: “We are 32,000 people, and just with the UK there is more than enough business.”
Mr Isola suggested that an agreement with Britain for continued “unfettered access to the UK market” has eased concerns, along with no “significant exit” of financial firms or jobs.
He added: “That gives us an opportunity to carry on as we are and potentially grow.”
The Minister warned that Gibraltar’s prospects for direct access to the EU were “not high” stressing they were far more critical to maintain “fluidity at the frontier” for a financial sector that accounts for a fifth of economic output.
He concluded: “In January 2021 there should be zero change at the border.
“Unless we have ‘punitive politics’, we will be absolutely fine, but that is a risk,” referring to recent negotiations with Spain.
A Gibraltar Government spokesman that the government was “currently preparing for all eventualities” which includes “preparations for leaving the transitional period on 31 December 2020 without an agreement”.