WASHINGTON - US President Donald Trump on Monday said antimalarial drugs that are under investigation to treat the new coronavirus could be a "gift from God" despite scientists warning against the dangers of overhyping unproven medicines.

Trump announced last week his administration was working to dramatically expand access to hydroxychloroquine and chloroquine, a related compound, following promising early studies in France and China that found the drugs helped patients suffering from the COVID-19 illness.

Many scientists including Anthony Fauci, the United States' leading infectious disease expert, have urged the public to remain cautious until larger clinical trials validate the smaller studies.

But Trump demonstrated no such restraint at a White House press briefing on Monday.

"The hydroxychloroquine and the Z-Pak, I think as a combination probably is looking very, very good," he said.

"There's a real chance that it could have a tremendous impact, it would be a gift from God, if that worked it would be a big game changer," he added, quoting the example of patient who was ill but recovered after taking the drug.

Trump has been criticized by some in the scientific community for overhyping the drugs -- which could create shortages for Americans who need them to treat lupus and rheumatoid arthritis, diseases for which they are approved.

New York is set to begin a clinical trial on Tuesday that would treat patients with hydroxychloroquine taken together with azithromycin, an antibiotic used to clear secondary bacterial infections.

Separately, Vice President Mike Pence announced that self-administered nasal swab tests for the illness would be made available this week, thus reducing part of the burden on the overstretched health care system.

At present, the test is administered by health care workers wearing personal protective gear which is in short supply.

The US has more than 40,000 cases and 500 deaths, according to a tracker maintained by Johns Hopkins University.

© Agence France-Presse