Banner saying "the Falkland Islands are and will always be Argentinian" (ALAMY)

Sir Nigel Sheinwald, Britain's ambassador to Washington until 2012, admitted to the committee that US position on the Falklands had been "uncomfortable...[and] not what we wanted".

Critics of the Obama administration argue that the current US stance does not even amount to "neutrality" since it calls for talks between Britain and Argentina in defiance of the clearly-expressed will of the Falkland islanders.

Luke Coffey, a former adviser to Liam Fox when he was Defence Secretary and now the Margaret Thatcher Fellow at the Heritage Foundation, a Conservative think-tank in Washington, said the US had clearly "abandoned its long held position of neutrality" in the dispute.

"Negotiations over the status of the Falkland Islands is the official Argentine position. Instead of keeping quiet (neutral), under Obama's leadership, the US has started backing Argentina's calls for talks. This is a change from previous administrations and a departure from neutrality," he said.

In other key areas, the report was positive, praising the Coalition government for taking a less supine position towards the US that during the Blair years and supporting William Hague's formulation of the relationship as "solid not slavish".

It also found that the Commons vote against military intervention in Syria last year had not damaged the Special Relationship instead demonstrating the underlying depth and resilience of US-UK ties - a position not universally agreed upon in the Washington foreign policy community.

"I think that's a very optimistic assessment," said Fran Burwell, Director of the Transatlantic Relations Program at the Atlantic Council. "Big events like this feed into the growing perception in Washington that EU nations are no longer ready and willing to do what is necessary."

The committee also fretted about the impact in the US of the promised 2017 referendum on British membership of the European Union if the Conservatives win the next election, warning that the America might start to "hedge" against an exit by deepening ties with other European capitals, to Britain's detriment.

Meanwhile, Argentine President Cristina Kirchner claimed on Wednesday that the Falkland Islands serve as a nuclear base for the Nato alliance in the South Atlantic.

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Britain is 'disappointed' with America over Falkland Islands, finds Commons report