The foreign woman, whose dead body was found on Sunday (6 November) on a yacht off Sulu in the Philippines, was possibly raped, the country's military said. The Philippine defence ministry confirmed that the woman was the wife of the German sailor Jurgen Kantner, who is under Abu Sayyaf captivity.

The militant group abducted the couple from their yacht, named Rockall, over the weekend off Laparan Island in Pangutaran, Sulu.

Delfin Lorenzana, the defence secretary, confirmed that the body that was recovered from the yacht was of 59-year-old Sabine Merz – the wife of Jurgen Kantner, 70. Local forces have launched a major operation to locate the militants and free the hostage.

Major Filemon Tan Jr., spokesman for the Armed Forces Western Mindanao Command (Westmincom), said on Monday (7 November) that the woman's body was found naked on the yacht and had several contusions to the face. Terming the incident as "alarming", he said that the woman was possibly raped.

He also said that Joint Task Force Sulu has alerted its units to intensify intelligence gathering to locate the Abu Sayyaf militants and the German hostage.

The same German couple luckily escaped Somali pirates in 2008 after being abducted by them in the Gulf of Aden. They were kept hostage for 52 days and were also subjected to a mock execution, Agence France Presse reported.

Kantner had told the news agency in an interview in 2009 that he would continue sailing despite threats to their life from sea pirates. "My boat is my life and I don't want to lose her, nothing more. I don't care about pirates and governments," he had said from the main port in Somaliland, where he had returned with his wife to retrieve his yacht, Rockall.

The Philippine military released a photograph of the boat on Monday. The yacht had a German flag on it. Tan reportedly said that passports of the German couple were recovered from the boat and the photograph of the German woman matched the body recovered the previous day.

Meanwhile, Jesus Dureza, the presidential adviser on the peace process, reportedly said the government would maintain its no-ransom policy.

"When I talk to them, I cannot talk about ransom. The government has a strong no-ransom policy," the Philippine Star quoted Dureza as saying. He had earlier interceded for the safe release of previous Abu Sayyaf victims, including a Norwegian citizen released in September.

Separately, there were reports of kidnappings of two Indonesian sailors off Sabah during the same time as the abduction of the German couple. The Indonesian foreign ministry confirmed receiving information about two separate kidnapping incidents of their sailors.

The ministry has cautioned its crewmen to avoid sailing in the vulnerable waters until security has been beefed up. They have also contacted Malaysian and Philippine government officials to deal with the situation.