LONDON (AFP) - Britain has emphatically rejected the European Union's claims that it had slapped a ban on coronavirus vaccine exports, in the latest spat over supply since Brexit took full effect.

European Council chief Charles Michel had said that London had imposed an "outright ban on the export vaccines or vaccine components produced on their territory".

But British Prime Minister Boris Johnson hit back, after government officials summoned a senior EU official for a meeting to "set the record straight".

"Let me be clear, we have not blocked the export of a single Covid-19 vaccine or vaccine components," Mr Johnson told lawmakers in Parliament on Wednesday (March 10).

"This pandemic has put us all on the same side in the battle for global health. We oppose vaccine nationalism in all its forms."

Mr Johnson's comments came after a swift denial from Foreign Secretary Dominic Raab on Tuesday night, who called Mr Michel's assertion "completely false".

Mr Michel later backtracked but not before the deputy head of the EU mission to the UK, Ms Nicole Mannion, was hauled into the foreign ministry, and London fired off a strongly worded letter.

The EU argues that while 30 per cent of the vaccines produced in the bloc have been exported, Britain has not published any data on how many vaccines produced on its soil have been sent overseas.

Britain has only two factories, which produce the AstraZeneca vaccine. The contract signed between the company and the British government gives priority to the domestic inoculation drive.

Mr Michel said he was shocked by accusations of "vaccine nationalism" against the EU after the introduction at the end of January of an export control mechanism for vaccines produced in the bloc.

Diplomatic bungle

More than 34 million doses of vaccines produced in the EU were exported between Feb 1 and March 9, including 9.1 million to the United Kingdom - more than a third of the total doses administered in the country so far.

The UK points out that it is one of the leading donors to the United Nations' Covax vaccine-sharing programme, which has started rolling out in Africa.

Mr Johnson told Parliament the country had so far contributed £548 million (S$1 billion) to the global fightback against the virus.

Despite the prime minister's statement, Brussels demanded answers - and hard figures - about what one EU official called "restrictive practices adopted by the United Kingdom".

"Our demand goes back further than yesterday," the official said.

The row is the latest in a series of cross-Channel rows over the vaccine since Britain fully completed its EU departure in January.

Nearly 23 million people have so far received a first jab in Britain - one of the highest numbers in the world.

But the EU is under pressure over its own inoculation strategy, and has partly blamed the Anglo-Swedish firm AstraZeneca for failing to fulfil its order because of production issues.

Brussels, Dublin and London were plunged into chaos on Jan 29 when the EU unveiled plans to unilaterally undo elements of the Brexit deal governing Northern Ireland to stop vaccines from leaving the bloc.

The special post-Brexit trade rules - painstakingly negotiated since Britain's 2016 decision to split from the bloc to guarantee peace in Northern Ireland - had been operating for less than one month.

An outcry from Britain, Ireland and Northern Ireland forced the EU into a speedy U-turn - reversing a plan now widely considered to have been a diplomatic bungle.