This is the first time during the pandemic that the Scandinavian country has closed the border on one of its neighbours.
“The new mutated virus has also been confirmed in Denmark and some other countries. But Denmark has also had an increased spread lately and elected to close down for example all shopping malls during Christmas and the holidays,” Home Affairs Minister Mikael Damberg told reporters.
“There is an obvious risk that Danes will be tempted to cross over to Sweden to shop for Christmas presents or spend time in Malmo for instance,” Damberg added.
Swedish citizens are exempt from the entry ban, as are non-citizens who live or work in Sweden, and people working in transportation of goods.
Like many other European countries, Sweden also imposed an immediate suspension of passenger flights from the UK, over the variant of the coronavirus that is reportedly up to 70 percent more contagious.
According to the World Health Organization (WHO) there is currently “no evidence to indicate any change in disease severity.”
Neighbouring Norway, Denmark and Finland have all imposed travel restrictions at times during the pandemic on Sweden, which has seen a much higher death toll than the rest of the Nordics.
Sweden, which has followed a controversial softer strategy to curb the novel coronavirus with mostly non-coercive measures, has tried to keep regional borders open.
“Now when we are closing libraries on the Swedish side, then it's not reasonable that Danish tourists should come and shop or go to a restaurant,” Damberg said.
Danish health authorities have reported nine confirmed cases of the new strain.
Faced with a strong second wave, Sweden has tightened preventative measures in recent months.
As cases multiplied, authorities urged people to limit social interactions to immediate family or a few friends.
A ban on public gatherings of more than eight people took effect last month, and last week the country for the first time recommended the use of face masks on public transport.