Sweden remains steadfast in its strategy of voluntary measures and no lockdowns, as the country battles a growing second wave of a disease that has now killed more than 6,000 Swedes.

The Nordic nation of 10 million people, whose soft-touch approach to combating the virus has drawn worldwide attention — and harsh domestic criticism from some — has seen a surge in the number of cases, hospitalisations and deaths in recent weeks.

At 5,990, the number of new cases reported on Friday (local time) was the highest since the start of the pandemic.

A further 42 deaths were also recorded, the most for about three months.

Swedish Prime Minister Stefan Löfven says the country is in "a very serious situation".

"The developments are going in the wrong direction fast. More are infected. More die," he wrote on Facebook this month.

The strategy, however, will not change.

"No, we will keep on this path," chief epidemiologist Anders Tegnell said.

"This is how we work in Sweden. We have [a] big understanding for this and a huge adherence to the rules."

In contrast to many other countries, Sweden has kept schools, restaurants and other businesses open throughout the pandemic.

Instead, it has focused on voluntary measures aimed at promoting social distancing and good hygiene, such as working from home if possible, and avoiding public transport and crowded indoor activities.

The approach has drawn criticism and praise.

Dr Tegnell's frequent press conferences have attracted large television audiences.

Several people have had his face tattooed on their bodies and T-shirts saying "In Tegnell we trust" can be spotted on the streets of Stockholm.

Not everyone agrees, however, and Dr Tegnell has received death threats from people accusing him of pursuing a reckless policy.

Scientists calling for politicians to override the Health Agency

While Sweden's death rate per capita is lower than in countries such as Spain and Britain, it is more than 10 times higher than neighbouring Norway and almost five times higher than in Denmark.

In an open letter published in the daily Aftonbladet newspaper, 27 Swedish scientists and doctors warned the country could soon approach the sort of numbers in intensive care seen in during spring.

The scientists called on party leaders to override the Health Agency and introduce tougher restrictions.

Sweden has recorded 485 cases per 100,000 people in the latest two-week period, roughly the same as Britain but just more than half that of France.

Dr Tegnell played down the criticism and said the recent lockdowns in Europe, which for the most part have been less strict than those in the spring, showed there was less of a difference in approaches to fighting the virus now.

"Most countries are now trying to do it a bit more like we have done in Sweden. Almost no-one is closing schools now, for instance," he said.