(Photo: Agencies)

WASHINGTON - Pharmaceutical giant AstraZeneca said Monday that trials showed its Covid-19 vaccine is 100 percent effective in preventing severe disease, as a row simmered between Britain and the EU over much-needed supplies of the jab.

The AstraZeneca shot is cheaper and easier to store than many of its rivals, but several countries in Europe and other parts of the world last week suspended its use because of isolated cases of blood clots.

It is also at the centre of a row between Britain and the EU, after Brussels threatened to ban exports to the UK unless the company delivers more of the 90 million doses it agreed to supply in the first quarter of 2021.

Irish prime minister Micheal Martin said such a move would be "a very retrograde step," while Britain's leader urged the European Union not to carry out its threat.

"We're all facing the same pandemic, we all have the same problems," Prime Minister Boris Johnson said on Monday.

The spat is mostly focused on a Netherlands factory that is still awaiting official EU approval, but which both sides claim as a future source of the AstraZeneca jab.