A possible preclearance agreement between the US and the UK could lead to stringent airport searches and interrogations by Homeland Security officials for UK passengers travelling to the US.
The Guardian newspaper is in possession of few documents that show that US authorities have approached the UK, the Netherlands, Germany, France and Sweden about setting up preclearance checks at European airports.
The UK is the only country so far to have shown an interest in the proposal, according to the documents. While the Netherlands will look into the financial and legal feasibility of the proposal, France has asked for financial support from the US in exchange for the deal. The German Government said that it was cautious about such proposals.
The Guardian quoted the document as saying: "Sweden's first reaction was to express scepticism, calling for further analysis of the consequences on the Schengen agreement on open borders in Europe and the European convention on human rights."
An official request for the preclearance proposal is yet to be submitted by the US.
The preclearance process aims to reduce congestion at the airport's entry and minimise the possibility of being denied entry to the US after a long-haul flight.
However, additional checks at the European end would mean an increase in financial costs to airport operators, as well as limit the flexibility with which airports assign departure gates.
Several European airports already have staff from the Department of Homeland Security, who can help determine which passengers should be denied entry to the US. Since flights carrying such passengers could be prevented from a US landing, the department's recommendations are usually taken into consideration.
According to a 2011 agreement between the US and EU, passenger data is shared with Homeland Security and US border authorities, who can exchange and retain up to 15 years of information on travel itineraries, passenger addresses and payment methods.
Ireland is currently the only country in Europe that has preclearance checks for passengers flying to the US.