JAKARTA, Indonesia (Updated) -- Indonesia's foreign affairs ministry said Tuesday they are putting up efforts to rescue 10 Indonesian crewmen who were kidnapped Saturday by terrorist group Abu Sayyaf off southern Philippines waters.

"To handle this case, the ministry continues to communicate and coordinate with all related institutions in Indonesia and the Philippines, including the foreign affairs minister of the Philippines," said Arrmanatha Nasir, spokesman of the Indonesian Foreign Affairs Ministry, in a statement on Tuesday.

"Our priority is the safety of all 10 Indonesians held hostage," the statement added.

The crewmen were on board two tugboats called Brahma 12 and Anand 12, which were reportedly carrying 7,000 tons of coal, en route from Puting river in Banjarmasin in Indonesia's South Kalimantan province to Batangas in the Philippines.

Reports from Manila said that local authorities found one of the tugboats abandoned at Languyan island, Tawi-tawi province Monday afternoon.

Arrmanatha said Brahma 12 was already in the custody of officials in the Philippines while the other vessel and crewmen were still held hostage.

The ministry said the owner of the hijacked tug boat and coal barge has received two telephone calls, purportedly from terrorist group Abu Sayyaf, demanding a ransom.

It does not know exactly when the incident occurred but said the ship owner was first contacted on Saturday, March 26. The ministry's statement also referred to the hostage takers as pirates.

The company that owns the ship has informed the families of the crew.

Abu Sayyaf, which is on US and Philippine lists of terrorist organizations, is notorious for bombings, extortions and kidnappings for ransom in the volatile south of the Philippines. It has been weakened by years of US-backed Philippine offensives but remains a security threat.

A report said authorities in the Philippines have received a demand for ransom equivalent to at least $1 million for the crew's release.

Security officials in the Philippines suspect the al-Qaeda-linked Abu Sayyaf for last year's abductions of two Canadians, a Norwegian and a Filipino woman from a marina on southern Samal Island. The kidnap victims are believed to be held in the jungles of southern Sulu province.

In a recent video posted on a Facebook account linked to the bandits, they threatened to kill the hostages unless a huge ransom was paid by April 8.

The Philippine military said the government's no-ransom policy remains and security forces would continue efforts to secure the safe release of the captives.

Indonesia has been helping the Philippines forge a peace agreement with Filipino Muslim rebels by sending soldiers to join an international oversight group that helps monitor government and rebel adherence to a ceasefire. (PNA/AP)