It is understood that the suspected pirates, who were believed to have been armed with at least three M16 rifles, robbed four men of their three outboard engines - two 15 horse-power engines and one pump boat engine - close to Sungai Bilis at about 11pm on Sunday.
A police General Operations Force patrol team came across the fishermen paddling back to the coast at about 1am Monday. A police report was lodged over the incident which officials state involved three separate sea robberies.
Sabah Police Commissioner Datuk Hamza Taib confirmed the incident.
It was learnt that senior Eastern Sabah Security Command (Esscom) officers and police are investigating if the pirates were from the area or foreigners.
Security agencies have stepped up patrols in the area in a bid to track down the pirates who could be beyond the Malaysian sea border.
Tanjung Labian including Sungai Bilis was the centre of Malaysian security forces operations to flush out Sulu gunmen who fled to the area following the shootout in neighbouring Kampung Tanduo on March 1, last year.
Esscom is already under a lot of pressure following two incidents in which foreigners were abducted from Semporna by Abu Sayyaf gunmen.
In early March, 29-year-old Gao Hua Yun from Shanghai and 40-year-old Marcy Dayawan @ Mimi were abducted from the Singgahmata Reef Resort in Semporna.
The incident occurred several months after a Taiwanese national, Chang An Wei, 57, had been abducted by armed men from Pom Pom island.
In the November incident, Chang's companion, Li Min Hsu, 57, died after being shot several times by the armed men.
Chang was freed a month later in December after a sizable ransom was reportedly paid for her release.
The fate of Gao and Marcy, however, is still not known although it is learned that the kidnappers have already made their ransom demands.
This has led both Barisan Nasional and Pakatan Rakyat lawmakers to describe Esscom as a waste of public funds.