AstraZeneca will increase its coronavirus vaccine deliveries to the European Union by 30 percent, European Commission President Ursula von der Leyen said Sunday as the bloc sought to claw back time lost rolling out the jabs.

The British-Swedish company had announced last week that it could deliver only a quarter of the doses originally promised to the bloc for the first quarter of the year because of problems at one of its European factories, which is managed by a sub-contractor.

But AstraZeneca, whose vaccine was authorized for use in the EU on Friday, has now agreed to send nine million additional doses and "will start deliveries one week earlier than scheduled," von der Leyen said in a tweet.

An EU source said the first deliveries would start in the second week of February.

AstraZeneca would also extend its production capacity in Europe, von der Leyen added. She told Germany's ZDF broadcaster the new doses represented an increase of 30 percent on the previous order.

"They are bringing forward the delivery now by another week ... and they will increase the vaccine doses for February and March by about 30 percent, that is nine million doses," von der Leyen said.

The EU leader was tweeting after talks Sunday with the leaders of the drugs companies that have signed vaccine contracts with the EU. According to the agreement signed last August, the European Commission, on behalf of the EU states, purchased 300 million doses, with an option to buy 100 million more.

'A difficult phase'

The EU's civil service is under fire over the slow pace of vaccination in the bloc, with critics pointing to faster progress being made in Britain, Israel and the United States as evidence of a planning failure in Brussels.

"I think the only race we are in is with the virus and against time," von der Leyen told German television on Sunday evening, adding that she had agreed with British Prime Minister Boris Johnson that factories in both regions would deliver doses to each region.

She also acknowledged that February and March would remain "a difficult phase" for vaccine supply.

In the second quarter, the Johnson & Johnson vaccine will be on the market "and the manufacturers will have resolved their initial difficulties, so we can expect more vaccine," she said.

On January 19, EU said it aimed to vaccinate 80 percent of the health professionals and people aged over 80 by March. But problems at AstraZeneca and with the Pfizer-BioNTech vaccine have threatened those plans.

The aim was still to vaccinate 70 percent of adults in the EU by the end of summer, von der Leyen promised.

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(With input from AFP)