But the British government says the European Union is an global organisation, rather than a country, and has not given Vale de Almeida the full rights accorded to ambassadors under the Vienna Convention, including immunity from taxation and prosecution.

Meanwhile London argues that the European Union envoy should only be given the lesser privileges awarded to global organisations, such as the worldwide Monetary Fund.

A Foreign Office spokesman said: "The EU, its Delegation and staff will receive the privileges and immunities necessary to enable them to carry out their work in the United Kingdom effectively". The new rules have put thousands of specialist online businesses at risk as consumers on both sides of the Channel balk at having to pay the hefty import fees.The UK government says European companies supplying goods valued at up to £135 direct to British buyers are supposed to collect Value-Added Tax at the item's prevailing rate - in most cases 20% - at the point of purchase.

Tobias Ellwood, also a former Foreign Office minister and current chairman of the Commons Defence Committee described the decision as "simply petty".

As it stands, the ambassador would not have the chance to present his credentials to the Queen like other diplomatic heads of mission.

"The EU has 143 delegations, equivalent to diplomatic missions, around the world", a European Commission spokesperson told the BBC.

The State Department, under new management, did not immediately respond to a request for comment.Richard Boucher, a former USA diplomat who served as Washington's envoy to Hong Kong and Macau under Bill Clinton, said it was logical that Beijing had waited for the curtain to fall on the Trump administration before announcing the measures."Countries don't normally put sanctions on serving officials because even under the most strained circumstances they have to deal with them", said Boucher, who assessed the measures as largely symbolic.

But Whitehall sources insisted that worldwide organisations were offered "very similar privileges and immunities" to diplomatic missions sent by foreign governments.

A British government source said the issue of the European Union delegation's status was subject to ongoing negotiations.

And ex-National Security Adviser Lord Ricketts said: "This is a wholly unnecessary move which seems part of a systematic effort to signal that the United Kingdom is shunning the European Union and all its works".

He said granting reciprocal treatment based on the Vienna Convention on Diplomatic Relations is "standard practice" between equal partners and we are "confident that we can clear this issue with our friends in London in a satisfactory manner".

Under the Vienna Convention governing diplomatic relations, envoys representing countries have certain privileges such as immunity from detention and, in some cases, prosecution, as well as tax exemptions.

The Foreign Office did not immediately respond to a request for comment.