German Chancellor Angela Merkel on Monday defended the European Union's troubled vaccine drive, saying there were "good reasons" the rollout had got off to a slower start than in some other countries.

Speaking after a vaccine "summit" that brought together key players, Merkel renewed a promise to offer every German citizen a vaccine by the end of September.

Merkel had convened the online talks in response to growing anger in the 27-member bloc over the sluggish rollout of Covid-19 jabs, which has been beset with delivery delays and piled political pressure on EU leaders.

"It is true that in some areas, the pace became slower, but there were good reasons for it to be slower," Merkel told reporters in Berlin. Merkel, the leader of Europe's largest economy, acknowledged that the United States, Israel and Britain were further along with their inoculations.

But she said the EU had deliberately avoided rushed emergency approvals, as seen in the UK, to bolster public "confidence" in the jabs.  The EU had also at times negotiated "for a very long time" to ensure pharma companies took on enough liability, she said. 

And the bloc chose not to sacrifice data protection, Merkel added, in a nod to Israel's deal with Pfizer/BioNTech to offer data on its inoculation campaign in exchange for doses.  German media has been scathing about the EU's troubled vaccine drive, with the top-selling Bild daily calling it a "disaster".

European Commission chief Ursula von der Leyen, a former German defence minister, has come in for particular criticism. A European source said Monday that Berlin was putting "tremendous" pressure on the Commission to improve the vaccine rollout, adding that von der Leyen's position had been "severely weakened".

Von der Leyen did not join Merkel's meeting with top German politicians, but the EU commissioners for health and the internal market did. A string of vaccine makers also took part, including Pfizer, BioNTech, AstraZeneca, Moderna, Johnson & Johnson and CureVac. "The months ahead will be challenging. We must all continue working together in solidarity to find solutions," said Health Commissioner Stella Kyriakides.