Tests on hamsters reveal the widespread use of facemasks reduces transmission of the deadly coronavirus, a team of leading experts in Hong Kong said Sunday.

The research by the University of Hong Kong is some of the first to specifically investigate whether masks can stop symptomatic and asymptomatic Covid-19 carriers from infecting others.

Led by Professor Yuen Kwok-yung, one of the world's top coronavirus experts, the team placed hamsters that were artificially infected with the disease next to healthy animals.

Surgical masks were placed between the two cages with air flow travelling from the infected animals to the healthy ones.

The infection rate plunged to just over 15 per cent when surgical masks were put on the cage of the infected animals and by about 35 per cent when placed on the cage with the healthy hamsters.