BANGKOK (The Nation/Asia News Network) - A Thai oil tanker was attacked by pirates on Friday (June 23) and robbed of 1.5 million litres of diesel fuel after leaving Singapore, officials said.

The ship, CP41, was loaded with 3.8 million litres of diesel when it was attacked by six armed men near Malaysia's Kuantan while heading from Singapore to the southern Thai province of Songkhla.

It then continued with its journey and arrived in Songkhla on Sunday.

The men, who spoke Bahasa, were equipped with guns and knives and entered the vessel, capturing the captain and crew members as well as destroying communications equipment before pumping 1.5 million litres of fuel into their ship and fleeing.

The captain and crew were safe and Thai authorities had been informed about the incident on Saturday night, hours before the tanker arrived in Songkhla, according to officials.

C&P Group, owner and manager of the vessel, is investigating the incident in cooperation with six agencies.

Thai navy's Vice Admiral Pornchai Pinthong said on Monday he had dispatched naval officers, customs officials, and officials from the Labour Welfare and Protection Department to visit the crew.

According to Pornchai, the robbery took place at just after 9pm on June 23 when the CP41 was in Malaysian waters at latitude 03 55.27 and longitude 103.52.81, off Kuantan.

He said six or seven pirates went aboard and rounded up the captain and 16 other crew and held them on the deck.

They destroyed the ship security alert system and robbed the crew of their valuables and stole some 1.5 million litres of diesel oil, then fled.

The ship was transporting some three million litres of diesel oil from Malaysia to Songkhla.

Pornchai said the Thai Navy had contracted the Malaysian Navy in a bid to locate the pirates.