One of the men was detained on unrelated charges of kidnapping and murder, while the other was carrying a gun and a grenade, said Superintendent Antonio Rivera, the police spokesman for the Davao region on the southern island of Mindanao.
Arrested together in Davao city on Sunday, the two are now being questioned over the September 21 abduction of three Westerners and the Filipina from the island resort of Samal near Davao, Rivera told AFP.
"We are looking at the (closed circuit) television footage" of the resort kidnappings to see if the two did take part, Rivera added.
Canadian tourists John Ridsdel, 68, and Robert Hall, 50, as well as Hall's girlfriend Marites Flor and Norwegian resort manager Kjartan Sekkingstad, 56, were seen being dragged away by gunmen in a boat in chilling footage earlier released by police.
Rivera declined to identify the detained men or give further details of the first suspect's alleged crimes.
It is feared the hostages have been taken to the heavily-forested southern island of Jolo, a stronghold of Islamic militants more than 500 kilometres (311 miles) from Samal.
Jolo is the main base of the Abu Sayyaf, an Al-Qaeda-linked group blamed for the country's deadliest terror attacks, beheadings and kidnappings of foreign tourists and Christian missionaries.
No group has claimed responsibility for the abductions. Mindanao has been plagued for decades by Muslim and communist insurgencies.
The Abu Sayyaf are known to hold four foreigners -- a Dutchman, a South Korean and two Malaysians -- according to the Philippine military.