Swedish media is reporting that the Emerald Princess cruiseship, which is due to tie up at Copenhagen harbour on Saturday, is carrying at least 14 patients suffering from the H1N1 flu virus.
According to Helsingborgs Dagblad, those infected are 13 crew and one passenger. The vessel is on its way to Warnemunde and Rostock via Helsingborg in Sweden and Copenhagen.
The Emerald Princess has 4,400 passengers and crew on board and it remains unclear whether the remaining passengers will be allowed ashore in the Danish capital.
"Initially we will be finding out how many have been infected and how ill they are," says Copenhagen Chief Medical Officer Arne Scheel Thomsen.
"(Copenhagen) hospitals are being informed that there can be a number of passngers or others who have to be admitted in order that they can be ready," Thomsen adds.
The national serum institute Statens Seruminstitut says the decision whether to quarantine the vessel is up to the medical officer.
"At sea, the captain's word is supreme. But prior to arriving in port, vessel authorities must inform the authorities there if there are infected people on board, and the Medical Officer then decides what to do," says Statens Seruminstitut Departmental Medical Officer Steffen Glismann.
Glismann says there have been cases previously in which vessels have been denied access to port.
"In one case a cruiseship was quarantined at sea for 14 days with all its passengers on board before it was allowed in," he says.
So far some 58 people have been infected with the H1N1 flu virus in Denmark. Thirty-seven of them contracted the flu abroad and 21 became infected in Denmark. There have been no fatalities in Denmark.
Edited by Julian Isherwood