Suspected Abu Sayyaf militants kidnapped three Indonesian fishermen over the weekend in the latest in a series of incidents highlighting weak security in the Celebes Sea that borders Malaysia, Indonesia and the Philippines.

The head of Indonesia's intelligence agency said Monday that the men were working on a Malaysian fishing boat off Lahad Datu in the Malaysian part of northern Borneo. Sutiyoso, who goes by one name, said the kidnappers fled with their hostages into Philippine waters.

"We suspect that the hostages are held by a militant group which is part of the Abu Sayyaf network," he said.

Several crew on the fishing boat escaped and are now in Malaysia.

Indonesian Foreign Minister Retno Marsudi said kidnappings can't be tolerated and urged the Philippines and Malaysia to ensure the safety of their territories.

She said defense ministers from the three countries will discuss plans to boost security at a meeting on Tuesday.

Indonesia, Malaysia and the Philippines agreed in May to carry out coordinated patrols in border waters following the kidnappings of Indonesian tug boat and barge crews by Abu Sayyaf militants based in the southern Philippines. The three governments are concerned that unchecked kidnappings, piracy and other crime could undermine commerce in the region.

The Indonesians, who were held captive in the jungles of Sulu province in the southern Philippines, were later released. The Indonesian government denied it had been involved in paying a ransom.

Including the incident over the weekend, a total of 24 Indonesian have been kidnapped by Abu Sayyaf militants this year.

The Philippines, meanwhile, has stepped up its military offensive against Abu Sayyaf, which earlier this year beheaded two Canadians it had held hostage since September.