An analysis of Stockholm's wastewater has shown an uptick in coronavirus cases in September to a level comparable to May, AFP reported while quoting researchers.

The researchers at the Royal Institute of Technology's (KTH) Water Centre said their method of taking virus measurements from wastewater meant their findings were not dependent on the level of testing for the novel coronavirus.

“In the study we can conclude that we are seeing a clear increase in the number of cases of Covid-19, that isn't due to more people being tested,” Zeynep Cetecioglu Gurol, associate professor at KTH, said in a statement.

The sampling of wastewater at three facilities in Stockholm began in mid-April, after studies showed that remnants of the virus could be detected in sewage water, but this is the first time broad results have been published.