MANILA (REUTERS) - The Philippines will not negotiate with Islamist militants demanding ransom within a month for the release of three foreign men and a Filipino woman kidnapped from a beach resort nearly six months ago, a military spokesman said on Friday (March 11).

Army units pursuing the band of al Qaeda-linked Abu Sayyaf militants, who are holding the two Canadians, a Norwegian and the Filipino woman, are closing in on them, Brigadier-General Restituto Padilla said.

"The policy on no negotiations with kidnappers includes no payment of ransom," Padilla told Reuters, dismissing the one-month deadline given by the militants as a ploy to relieve the military pressure they are facing.

"We're getting closer to them, hence, they needed to expedite the demand for ransom in order for them to escape from the hands of the law, which is closely catching up."

The four hostages were kidnapped from a beach resort on a southern island in September last year. They are believed to be held in the jungle on Jolo island, a stronghold of the Abu Sayyaf, who are known for bombs, beheadings and kidnappings.

In a minute-and-half video clip posted on an Islamist-linked Facebook account on Thursday, the three foreigners appealed to their governments to meet the militants' demands, saying if not they faced execution.

It was the third time the militants had released such video appeals from the captives.

Though no specific ransom was mentioned in the latest clip, in November, one of the captives said the militants were demanding one billion pesos (S$29 million) for each of them.

The men's embassies in Manila have declined to comment to the media on their cases but Padilla said the military was working closely with their governments to secure their release.

The army was pursuing the militants "relentlessly" and wanted to "help address this issue once and for all", he said.

In the past, the rebels have killed at least two foreign hostages and one was killed during an army rescue attempt.

The September raid on the resort was a reminder of the precarious security in the resource-rich south of the largely Christian Philippines despite a 2014 peace agreement with the largest Muslim rebel group that ended 45 years of conflict.

Abu Sayyaf militants are holding other foreigners including one from the Netherlands, one from Japan, and an Italian missionary.