A fire that broke out on a passenger vessel with 300 people on board off Sweden's coast on Monday has been extinguished and no injuries were caused, Swedish maritime authorities said.

The blaze was believed to have started on a refrigeration lorry on the car deck of the Stena Scandica, which was sailing from Sweden to Latvia.

"The ferry will be towed to port in the next three to four hours", Swedish Maritime Administration spokeswoman Lisa Mjorning said, adding that it would be towed to Nynashamn, south of Stockholm.