Hong Kong will close two cruise terminals and will put anyone coming from mainland China into compulsory quarantine for 14 days, its leader Carrie Lam said on Wednesday. The move is part of fresh clampdown against contagion.

Lam said the measures were aimed at curbing the cross-border flow of people to prevent the spread of a new coronavirus, which originated on mainland China. Some medical staff have been on strike for the past three days, demanding a full border closure. There have been 21 confirmed cases in Hong Kong, according to Lam.

Passengers and crew on a cruise ship that docked in Hong Kong on Wednesday were being kept on board while they were tested for a coronavirus. The cruise ship, World Dream, operated by Dream Cruises, docked in Hong Kong after it was denied entry to the Taiwan port of Kaohsiung on Tuesday, Reuters said. It has some 1,800 passengers and a similar number of staff on board.

Three mainland Chinese who had been on board from January 19 to January 24 were found to have had the virus, Hong Kong's health department said, adding that most of those remaining on board were from Hong Kong. Some crew had reported symptoms including fever, health officials said.