British pharma giant AstraZeneca is "on track" to begin rolling out up to two billion doses of a coronavirus vaccine in September if ongoing trials prove successful, its chief executive said on Friday.

The company is partnering with Oxford University, which has pioneered the vaccine, and is already manufacturing doses before seeking final regulatory approval once testing concludes in the coming months.  

"So far we're still on track... we are starting to manufacture this vaccine right now, and we have to have it ready to be used by the time we have the results," AstraZeneca chief executive Pascal Soriot told BBC radio.

"Our present assumption is that we will have the data by the end of the summer, by August, so in September we should know whether we have an effective vaccine or not."

The firm announced this week it had struck agreements with the Coalition for Epidemic Preparedness Innovations (CEPI), Gavi the Vaccine Alliance, and the Serum Institute of India to double production capacity of the COVID-19 vaccine to two billion doses.

The partnership with the Indian institute -- one of the world's largest vaccine manufacturers -- will help supply it to a large number of low- and middle-income countries.

AstraZeneca has established separate supply chains for the vaccine in Europe, the United States, India and is also looking at setting up production in China, Soriot said.

He added AstraZeneca, which is undertaking the work on a non-profit basis, could lose money if trials prove disappointing.

But he said the company was sharing the financial risk with organisations such as CEPI.

"We're manufacturing indeed at risk -- and that's the only way to have the vaccine ready to go if it works," he added.

Oxford University began initial trials of its COVID-19 vaccine with hundreds of volunteers in April, and is now expanding them to 10,000 participants.

It said last month they were "progressing very well".

Researchers announced this week they will also start tests in mid-June in Brazil, the first country outside Britain to take part in the study, as the South American country's virus infection rate spirals while the UK's falls.