Bangkok (AFP) - For Bangkok market sellers, the armpit sweat soaking their T-shirts during the humid monsoon season may contain subtle signs of coronavirus infection, local scientists have said.

Thai researchers are developing a sweat-based mobile virus detector, and road-tested it on shopkeepers at a Bangkok food market this week.

"From the samples, we found that people infected with Covid-19 secrete very distinct chemicals," said Chadin Kulsing from Bangkok's Chulalongkorn University.

"We used this finding to develop a device to detect the specific odours produced by certain bacteria in the sweat of Covid-19 patients.

Chadin -- who said the test was 95 percent accurate -- hopes it might be rolled out as an affordable alternative to more expensive swab tests that require lab processing.

It is however still in the development stage, and the research behind it is yet to be published or peer-reviewed.

The scientists adapted a device usually used to detect toxic chemicals in the environment.

Subjects place a cotton swab under their arms for 15 minutes, before the swab is put in a glass vial and sterilised with UV rays.

"The technician then draws an appropriate amount of the sample using a suction hose, and pressurises it into the analyser to check the results," Chadin said.

Sample collection takes 15 minutes and the results are ready in 30 seconds.

The sweat tests received the thumbs-up from Bangkok market vendors, who said it was much more pleasant than nostril swab tests.

"This sweat test is more convenient because I get to work while waiting for the results," a 43-year-old watermelon seller told AFP.

"With the PCR test, I'd have to be at a testing centre, sit and wait for the result and it just wastes my time."

Thailand, battling its third and worst Covid wave, reported 16,000 new cases Thursday, taking the total since the start of the pandemic to nearly 1.34 million.