A cyberattack targeting coronavirus data at the EU's medicines watchdog lasted two weeks but will not affect the timeline for approval of the jabs, the head of the regulator said on Thursday.

The European Medicines Agency announced the cyberattack on Wednesday but gave few details, while Pfizer-BioNTech said documents relating to its regulatory submission were illegally accessed.

"We have been subject of a cyberattack over the last couple of weeks. This is being investigated," EMA chief Emer Cooke told a European Parliament committee.

"I can assure you that this will not affect the timeline for the delivery of vaccines and that we are fully functional," she added.

The Amsterdam-based EMA was probing the hack "in conjunction with experts from cybersecurity authorities across the EU, and with the criminal authorities and the Dutch police."

The agency has said it will give a decision on conditional approval for Pfizer-BioNTech's Covid-19 vaccine at a meeting to be held by December 29 at the latest, while a ruling on Moderna's version should follow by January 12.

Cooke said based on the data for the two vaccines so far, "the safety and efficacy look very promising, and we have not seen the adverse events coming up that would be a concern."