Covid cases in Scotland could be "substantially higher" than the one in 30 people estimated to have the virus, an expert has warned.

Prof Rowland Kao told the BBC that the lack of testing and monitoring meant infection levels were unknown.

According to the Office for National Statistics (ONS) cases have risen from one in 40 the previous week.

The latest data estimates that 176,900 people in Scotland had the virus - about 3.36% of the population.

Prof Kao, an epidemiology expert from the University of Edinburgh, said: "One of the things is that we actually don't know how much Covid is out there, because we no longer do surveillance for it.

"So that one in 30 is probably substantially higher."

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He told BBC Radio Scotland's Good Morning Scotland that rising Covid numbers were linked to the emergence of a new variant which is "slightly different" from the Omicron .

This version of the virus is now the predominant one in the US.

"We think it is probably more transmissible than the previous variant, so that is one of the big things," he added.

Prof Kao said governments were "doing very, very little" to control the virus, which was contributing to an increase in cases.

He said: "We're essentially going about our daily businesses as usual and we are not testing.

"And that not testing means we are not even able to pick up the disease, we also don't know how much is out there."

The estimated Covid rate in Scotland is higher than in England, where it is believed one in 50 people had coronavirus in the week ending 11 June.

In both Wales and Northern Ireland the estimated rate was one in 45 people.

Last week experts said a return to Covid restrictions was not currently needed as infection rates rose in Scotland.

Prof Kao said current versions of the virus were similar to the common cold, but it remained important to isolate if you developed symptoms

Severe illness

"By far, removing people who are infectious from contact with others is the most important thing we can do to prevent the transmission of disease," he said.

"For most of us Covid is relatively minor, we don't have too many symptoms, but people are still getting long Covid, so even healthy people can have quite severe symptoms for a while and some people are at risk of severe illness and death.

"The key thing is, if you have symptoms you should try to isolate, even if you are not sure it is Covid.

Prof Kao's comments come after warnings on Friday that Scotland is experiencing another wave of the virus.

Edinburgh University public health expert, Prof Linda Bauld, has said the Omicron sub-lineages BA.4 and BA.5 were part of the reason for the increase in cases.

She told the BBC there had also been a "small but not significant" rise in the number of people in hospital.