French pharmaceutical giant Sanofi is donating 100 million doses of a malaria drug being tested for use as a treatment against the new coronavirus.

The company said in a statement on Friday that the hydroxychloroquine doses will be given to 50 countries.

Sanofi is also ramping up production, aiming to quadruple is capacity to manufacture the drug.

The company said it “will continue to donate the medicine to governments and hospital institutions if ongoing clinical studies demonstrate its efficacy and safety in Covid-19 patients”.

But it also warned that hydroxychloroquine has “several serious known side-effects” and tests are so far inconclusive over its safety and efficacy in treating Covid-19.

“While hydroxychloroquine is generating a lot of hope for patients around the world, it should be remembered that there are no results from ongoing studies, and the results may be positive or negative,” it said.

US President Donald Trump has been among the drug’s proponents, tweeting that hydroxychloroquine plus an antibiotic could be “one of the biggest game changers in the history of medicine” and should “be put in use immediately”.