The virus responsible for Covid-19 can remain infectious on surfaces such as banknotes, phone screens and stainless steel for 28 days, researchers say.

The findings from Australia's national science agency suggest SARS-Cov-2 can survive for far longer on surfaces than previously thought.

The virus is most commonly transmitted when people cough, sneeze or talk.

But experts say it can also be spread by particles in the air, as well as on surfaces such as metal and plastic.

Previous laboratory studies have found that SARS-Cov-2 can survive for two to three days on bank notes and glass, and up to six days on plastic and stainless steel, although results vary.

But the latest research from Australian agency CSIRO found the virus was "extremely robust," surviving for 28 days on smooth surfaces such as glass found on mobile phone screens and both plastic and paper banknotes, when kept at 20C (68F), which is about room temperature.

In comparison, the flu virus can survive in the same circumstances for 17 days.

The experiments were carried out in the dark, as UV light has already been shown to kill the virus.

"Establishing how long the virus really remains viable on surfaces enables us to more accurately predict and mitigate its spread, and do a better job of protecting our people," said CSIRO chief executive Dr Larry Marshall.

The study, published in Virology Journal, found the virus survived for less time at hotter temperatures; it stopped being infectious within 24 hours at 40C on some surfaces.

It also stayed longer on smooth, non-porous surfaces than on porous materials such as cloth, which was found not to carry any infectious virus past 14 days. (BBC)