The Filipino terrorist organization Abu Sayyaf, which recently pledged loyalty to the Islamic State (ISIS), is holding two German citizens captive and demanding 250 million Philippine Pesos (over $5.6 million) from Germany within 15 days - or they will kill the hostages. The two Germans, aged 55 and 71, were abducted in April from their sailing yacht in Palawan in the western Philippines according to the German-language news source T-Online . A Twitter account linked to the group called "IslamicStateMaldives" was cited by the German site as giving Germany until October 10 to pay up, and also demanded Germany stop "killing our brothers," a reference to the airstrikes Germany is supporting in the newly formed US coalition hitting ISIS terrorists in Syria and Iraq. An image of the two Germans being held by their Al Sayyaf captors can be seen here (for those unable to see the embedded Tweet, the Twitter image can also be viewed here ): Filipino police reportedly suspect the two are being held in the Muslim province of Sulu in the southern Philippines. G erman officials have so far declined to comment. Singapore's The Straits Times reported this Monday that the Malaysian state of Sabah raised its terror alert to red after Abu Sayyaf leader Isnilon Hapilon declared his loyalty to ISIS. Hapilon, who has a bounty of 16 million Malaysian Ringgits (just under $5 million) on his head, posted a video with masked terrorists from his group to YouTube in July pledging allegiance to the Islamic State, but only recently has the video been gaining notice on social media. The video can be seen here: