Norwegian Kjartan Sekkingstad (left) sits with Canadian Robert Hall, who was executed last month by Abu Sayyaf. (Reuters)

Philippine militant group Abu Sayyaf has threatened to behead the fourth and final hostage kidnapped from a quiet marina resort last September.

On Sunday night local time, the group's spokesperson Abu Rami called journalists in the Philippines to say the group planned to behead Norwegian Kjartan Sekkingstad on Monday, local time.

"There is no more ultimatum, we are going to behead this Norwegian anytime today," Rami told the Mindanao Inquirer.

As the day drew to a close in the Philippines, there was no word yet of whether the group had carried out their threat.

Rami's words followed the beheading of two Canadian hostages who were also kidnapped from the Oceanview Marina on Samal Island. The group executed Canadians Robert Hall and John Ridsdel after the Abu Sayyaf spokesperson said their ransoms of about $6.2 million each were not paid.

Hopes were raised for Sekkingstad's release late last week as the IS-affiliated group asked to negotiate with incoming president Rodrigo Duterte's administration — naming Presidential Peace Advisor Secretary Jesus Dureza.

Dureza reportedly assigned officials to negotiate with Abu Sayyaf, but said they would not discuss ransom payments.

When talks of a ransom were ruled out, Abu Sayyaf decided to behead the hostage, Rami told the Inquirer.

Reports that officials refused to pay the ransom appears to contradict efforts to secure another hostage, Filipina Marites Flor, who was released on June 24. Local media have reported she was released after a ransom payment—though it's not clear who may have paid it.

In that case, Duterte said he and officials negotiated for her release, Asia One reported.

Flor was kidnapped alongside Hall, Ridsdel and Sekkingstad in September. On June 24, Flor's captors freed her by dropping her off at a local politician's house.

Duterte has made it his mission to eradicate Abu Sayyaf, which enjoys a degree of sympathy and support from locals in the predominantly Muslim southern Philippines.

"Kidnapping must stop. It has given us a very bad image," Duterte said in a speech following Flor's release.

On Monday, an Armed Force chief proclaimed the new administration's strategy will be one of "shock and awe."

The military has been on the offensive in recent months, claiming to be hitting Abu Sayyaf strongholds hard. But questions followed the military's approach in early April, when Abu Sayyaf militants killed 18 soldiers and injured 52 others—though the group is only believed to have about 400 fighters in the southern Philippine archipelago.

"You will see in July that there will be shock and awe," Armed Forces chief Lt. Gen. Ricardo Visaya told reporters. "You are going to see results. It will be a different approach."