GENEVA (AFP) - The coronavirus pandemic has not deterred the Swiss from sending yodels echoing across their mountain valleys, but a concert attended by 600 people is believed to have made one canton a European coronavirus hotspot.

At the late September yodelling event in the rural Schwyz canton, people in the audience were asked to maintain social distancing, but mask-wearing was not required.

"We can't do anything about what happened with this yodelling group. We found out nine days after the performances that several people from the group were infected," event organiser Beat Hegner told RTS public television.

Now the pandemic has spread through the region, with 1,238 cases compared with just 500 in mid-September.

On Wednesday (Oct 14) alone, 94 people tested positive, twice as many as the day before.

The health minister warned on Thursday that the situation is "deteriorating" at an alarming rate.

"We have in recent days faced a new dynamic, which is very negative and very strong," Alain Berset told reporters. For the past week, he said "the situation in Switzerland is deteriorating faster than elsewhere."

At first glance, the Swiss figures may not seem that impressive compared with the soaring infection numbers in neighbouring countries.

The wealthy Alpine nation of 8.5 million people registered 2,600 new cases on Thursday - the highest daily number since the start of the pandemic.

Swiss President Simonetta Sommaruga warned on Thursday that a full-blown second wave was looming.

"It is five minutes to midnight," she told reporters, urging everyone in the country to take precautions.

"The swifter we act, the less restrictions there will be for the population, the economy, families and risk groups," she said, urging everyone to "work together".

The Swiss government is due to discuss whether fresh measures are needed to rein in the spread of the virus.

Switzerland has lifted most of the measures imposed during the first large wave of infections in the spring. Face masks are mandatory on public transport throughout the country, but only around half of the 26 cantons require them in shops and other public indoor spaces.

In Geneva, the hardest-hit canton, authorities this week meanwhile imposed a limit for spontaneous private gatherings of just 15 people, while demonstrations are limited to 100 people.

Switzerland has also slapped a mandatory 10-day quarantine on anyone arriving from a long line of countries, as well as on anyone who has been in contact with a known sufferer the virus - including Economy Minister Guy Parmelin.

The overloaded cantonal hospital in Schwyz has asked people to begin wearing masks and avoiding gatherings.

"There's an extremely high rate of positive tests. We've gone from 30 to 50 percent," hospital chief Franziska Foellmi said.

"It's time we reacted. The explosion in the number of cases in Schwyz is one of the worst in all of Europe," chief doctor Reto Nueesch posted online.

Cantonal authorities have stepped up infection control measures, making mask-wearing compulsory at all public and private events with more than 50 people and in situations where distancing can't be maintained.

But people can still go to the shops without covering their nose and mouth.

Switzerland isn't the only country to practice yodelling, an age-old style of singing where the performer rapidly switches between registers.

It's also practised in Austria's Tyrol region and in variant forms across the mountains of central Europe, from Poland to Romania.

Like archery, wrestling and the Alpine games, yodelling has been one of the building-blocks of common identity between Switzerland's culturally disparate regions since the 19th Century.