A maritime news portal says armed guards stopped an attack on a Danish-owned vessel when they exchanged fire with suspected pirates.
Maritimedanmark.dk says no one was injured on the Singapore-registered Brattingborg that has a Thai crew in Thursday's attack.
Shipowner Lars Steen Rasmussen was quoted as saying it was the first time the company had armed guards on one of its ships. He could not be reached for comments.
The attack comes days after suspected Somali pirates captured a Danish yacht in the Indian Ocean.
Earlier Thursday, the head of a private security company said his guards retook a yacht from Somali pirates after the Dutch couple on board locked themselves in a safe room.
Thomas Jakobsson of Naval Guards said Thursday that six of his guards were accompanying the Capricorn yacht on a separate motorboat. Six armed pirates were able to get aboard the Capricorn but the Dutch couple barricaded themselves in the boat.
Jakobsson says his men had a brief exchange of fire with the pirates before retaking the Capricorn with no casualties on either side.