No traces of coronavirus have been detected on London’s public transport network in tests dating back to October, researchers said.

Experts from Imperial College London are taking air and surface samples every month on a London Underground journey between two major stations, and on a bus ride in the capital.

Samples are taken from station concourses and commonly touched surfaces such as ticket machines and escalator handles.

All the results have tested negative, including for variants of coronavirus.

Dr David Green, senior research fellow at Imperial, said the findings from the “very sensitive” testing are “reassuring for passengers”.

He told the PA news agency a number of factors are contributing to the negative results, including Transport for London’s enhanced cleaning regime, the requirement for passengers to wear face coverings, and the reduction in demand.

“It shows that we’re taking the necessary precautions to minimise the risk of transmission on the Underground network,” he said.

Dr Green added that the tests will be useful when coronavirus restrictions are eased.

“It will be an early warning system to tell us, ‘is the risk of transmission on transport networks becoming more likely as more passengers return to the networks?’,” he said.

“We do need to keep social distancing in mind, and we do need to keep wearing masks because these are the reasons that the virus transmits between humans.

“It’s through aerosol transmission, it’s through touching surfaces, it’s through being very close to other people.”