Self-styled Islamic militants in southern Philippines have threatened to harm a Filipino and three western hostages they seized from an island resort last September, according to a video they posted online and verified by the army Friday.

In the video, heavily armed members of the Abu Sayyaf group could be seen surrounding the hostages, with the western captives on the ground heavily emaciated and bearded. One by one the hostages were made to speak as a bandit held a machete to one of the captive's neck.

“I am a Canadian citizen being held by the Abu Sayyaf group for ransom. The amount is, I do not know what it is. But the Canadian government has got to get us out of here fast, to do what is necessary to get us out here soon. We got one month before this happens,” said one of the hostages who identified himself as Robert Hall.

Hall was seized along with his Filipino girlfriend Marites Flor, fellow Canadian tourists John Ridsdel and Norwegian resort employee Kjartan Sekkingstad from a beach resort in the island of Samal in southern Philippines late last year.

Hall identified their captors as the Abu Sayyaf, or "Bearers of the Sword," a small band of militants that once fought for an independent Islamic state in the south but is considered a bandit group by the military.

The group gained international prominence in 2000 when it seized and successfully ransomed off for millions of dollars dozens of hostages, including Europeans and Malaysians seized in a cross-border raid into a Malaysian resort. The group also has been accused of attacks, including the firebombing of a passenger ferry on Manila Bay that killed over 100 people, in what is considered as the worst terrorist attack in the country so far.

The group has been known to harbor other foreign militants, and a heavily masked man who appeared on the video could be heard giving a one-month deadline for Manila to pay the money. The hostages said they would be killed by April 8, if no ransom was handed over.

The ransom amount was not specified in the video, but Abu Sayyaf had earlier demanded $21 million for each of the foreign captives. They did not specify a condition for Flor’s release.

The military, in a statement to International Business Times, condemned Friday the "inhumane treatment" of the hostages, which are believed held in the near-inhospitable jungles of Jolo, a southern island that is a known bailiwick of the Abu Sayyaf.

"Our troops are continuously conducting intensified combat operations to search and neutralize the terror group Abu Sayyaf and prevent them conducting terroristic activities," Major Filemon Tan, a spokesman for the military in the country's south, said in a statement to IBT.

He said troops "will get these terrorists sooner or later, it's just a matter of time."

The Philippines has been cooperating with the United States, which has been sharing intelligence data against the Abu Sayyaf. And, there have been recent reports that regional terrorist groups from Malaysia, Indonesia and the Philippines may be working to establish links with Islamic State militants.