STOCKHOLM, March 4 (Reuters) - Sixteen new cases of the coronavirus were confirmed in Stockholm, regional authorities said on Wednesday, taking the total number of cases in Sweden to 52.

"Sixteen additional patients were found infected with covid-19...The infected patients are being cared for in isolation to reduce the risk of further transmission," Region Stockholm said in a statement.

The causes of four of the 31 confirmed cases in the Stockholm region remain under investigation, as - unlike the rest of the cases - no clear link to infection abroad or contact with people who had been infected abroad was found, the authority said. (Reporting by Colm Fulton; Editing by Angus MacSwan)