Some 59 soldiers tested positive for the British variant of the virus at the NBC 77 training school in Spiez in central Switzerland, while a further 87 have been quarantined, the ministry said.

Fortunately, there are no serious cases," it said in a statement.

"Clarifications to determine how the virus may have spread through the school on such a scale are still ongoing."

The school provides basic training to all nuclear, biological and chemical defence troops, instructing exploration, detection, laboratory specialist and decontamination soldiers.

"The school's training service is temporarily suspended," the statement said, adding that army medics were looking after those infected with the virus.