MANILA (REUTERS/AFP) - Al Qaeda-linked Islamist militants in the Philippines released two German hostages on Friday, a senior police official said. The Abu Sayyaf group had originally threatened to behead one of the captives earlier in the day.

The hostages, captured by the militants in April from a yacht on the high seas, were being held in the interior of the remote island of Jolo, 960km south of Manila.

They were identified to AFP as Stefan Okonek, who is in his 70s, and his partner Henrike Dielen, in her 50s.

"They are now safe and secure at an army camp," the police official, who was not authorised to speak to the press, told Reuters.

He said soldiers and police officers had fetched the man and woman at a police checkpoint. The official was confirming a statement by Abu Rami, the spokesman for the small but violent group, to a commercial radio station based in Zamboanga city in the south that the hostages had been freed.

The rebels had demanded a 250 million pesos (S$7 million) ransom and for Germany to stop supporting US-led air strikes in Syria. They had threatened to kill one of the captives on Friday afternoon. Rami said Abu Sayyaf had received the amount in full. His claim could not be immediately verified by Philippines officials.

German government sources told Reuters that Foreign Minister Frank-Walter Steinmeier had sent a special envoy to the Philippines to negotiate a deal with the rebels. The envoy, Ruediger Koenig, arrived in Manila on Thursday evening.

The rebels have a record of kidnappings, killings and bombings.

Some Muslim groups in the southern Philippines have long been fighting Manila's rule, but Abu Sayyaf burst to prominence in 2000 after kidnapping 21 tourists and workers from a dive resort in nearby Malaysia.