The spokesman for the Abu Sayyaf announced on Thursday that the German government had been granted a new ultimatum for complying with the group's demands.

The group, which has links to al Qaeda, is demanding a ransom of 250 million pesos (4.4 million euros/$5.6 million) for two German nationals it has been holding since April. The release of the captives is also contingent on Germany's halting its military support of the US-led airstrikes against "Islamic State" (IS) fighters in Syria and Iraq.

"After October 17, 2014, Friday, at 3 p.m. (0400 UTC), you will not see one of them alive. It will be seen by the public so that we can show that we are not playing games," Abu Sayyaf spokesman Abu Rami told local radio in the southern Zamboanga City in an apparent telephone interview.

IS militants have beheaded several hostages in recent months as a brutal tactic to capture international media attention. It remains unclear whether Abu Sayyaf has links to that group.

Stefan Okonek, 71, and Henrike Diesen, 55, are believed to have been kidnapped at gunpoint from their yacht between Malaysian Borneo and the southern Philippines in April. Earlier this week, the pair pleaded for the German government to secure their release.

In late September, the German Foreign Ministry announced that Abu Sayyaf's tactics were "not an appropriate way to influence policy in Syria and Iraq."

kms/mkg (Reuters, dpa)