MANILA: A threat by Philippine militants to kill a German hostage in a show of solidarity with Islamic State is the latest sign that the Middle East group's brand of radicalism is winning recruits in Asia and posing a growing security risk in the region.

Over 100 people from Southeast Asia's Muslim majority countries of Indonesia and Malaysia and the southern Philippine region are believed by security officials and analysts to have gone to join Islamic State's fight in Iraq and Syria. Malaysian and Indonesian militants have discussed forming a 100-strong Malay-speaking unit within Islamic State in Syria, according to a report from a well-known security group released this week.

Admiral Samuel Locklear, who heads the US Armed Forces' Pacific Command, said on Thursday around 1,000 recruits from India to the Pacific may have joined Islamic State to fight in Syria or Iraq. He did not specify the countries or give a time-frame.

“That number could get larger as we go forward,” Locklear told reporters at the Pentagon. In addition to India, the Hawaii-based Pacific Command's area of responsibility covers 36 countries, including Australia, China and other Pacific Ocean states. The command does not cover Pakistan.

In the region, thousands have sworn oaths of loyalty to Islamic State as local militant groups capitalise on a brand that has been fuelled by violent online videos through social media, security analysts say. Security officials say this has disturbing implications for the region, especially when battle-hardened fighters return home from the Middle East.

The Philippines' Abu Sayyaf group, which has earlier claimed links with al Qaeda and is led by a one-armed septuagenarian, has threatened to kill one of the two Germans it holds hostage by Oct 10, according to messages distributed on Twitter. As well as $5.6 million in ransom, the group demanded that Germany halt its support for the US-led bombing campaign launched against Islamic State this week.

A spokeswoman for the German foreign ministry told a regular press briefing in Berlin that “threats are no appropriate way of influencing German foreign policy”, and that the ministry's crisis group was working on the case.

The Abu Sayyaf, which beheaded a US man it had taken hostage in 2001, has suffered from dwindling support and military setbacks over the past decade, and is now believed to have only about 300 followers based on remote islands off the southern Philippines.

Oath of loyalty

Security officials doubt it has any links with Islamic State beyond pledging allegiance to the Middle Eastern group, and see it as a move by Abu Sayyaf to revive its fortunes and gain publicity. A senior leader of the group and several other members made an oath of loyalty to Islamic State in a video uploaded on YouTube in July, Philippines police and monitoring services have said.

“We believe that there is no direct link, that they are possibly sympathisers joining in the bandwagon to gain popular support,” said Ramon Zagala, a military spokesman. “We see this as a way to be known, because right now the Abu Sayyaf is in a decline. To directly say that ISIS (Islamic State) is here - there are no indications of that.”

The German man and woman, who were reportedly seized from a yacht in the South China Sea in April, are thought to be held on southern Jolo island by Abu Sayyaf fighters loyal to one-armed Radullan Sahiron. His group is also believed to be holding a Dutch and a Swiss hostage seized in May 2012 and a Japanese man. The three governments have declined comment on the abductions.

Another Abu Sayyaf leader, Isnilon Hapilon, swore allegiance to Islamic State in the Youtube video, police officials and the monitoring services said. Speaking in Arabic, he and several other men read a statement swearing “loyalty and obedience in adversity and comfort” to Islamic State and its leader Abu Bakr al-Baghdadi before a prayer and shouts of Allahu Akbar (God is Greatest), they said.

Abu Sayyaf says it is fighting for an independent Islamic state but it has mainly been a kidnap-for-ransom gang operating in the lawless interiors of southern Philippines islands. The Philippines is mostly Christian but has a significant Muslim minority in the southern islands.

The region is the site of a long drawn-out rebellion by local Muslims against Manila's rule, but Abu Sayyaf burst into prominence in 2000 after kidnapping 21 tourists and workers from a dive resort in nearby Malaysia. They held the hostages, who included French, German, Finnish and South African nationals, for months on Jolo before freeing them for millions of dollars in ransom paid by then Libyan leader Muammar Gaddafi, according to Philippine officials. Libya denied it paid a ransom but acknowledged government officials were involved in negotiations. Several of the hostages visited Tripoli after their release.

Abu Sayyaf is blamed for the worst militant attack in the Philippines, the sinking of a ferry in Manila Bay in 2004 in which 100 people were killed. But the group has declined in recent years, with top leaders either killed or too old.