SENTUL, Indonesia (Reuters) - Indonesia's counter terrorism chief on Friday appealed to Southeast Asian neighbours to quickly step up intelligence-sharing efforts and combat fears that fighters returning from Syria could wage Paris-style attacks.

Indonesians fighting for Islamic State could supply the training, funds and organizational skills to weld the country's many splintered militant groups into a serious threat, said Saud Usman Nasution, head of the National Counter Terrorism Agency.

"We have to anticipate returnees and that must be done through cooperation and intelligence-sharing with many countries in the region," Nasution told Reuters in his office outside Jakarta, capital of the country with the world's largest Muslim population.

"If these countries have information about the movement of jihadis there, then it must be shared." Nasution said he did not see a specific or credible threat of an attack in Indonesia in the near future, however.

Terrorism will be high on the agenda when Southeast Asian leaders gather in the Malaysian capital of Kuala Lumpur this weekend for a regional summit.

This week, a Malaysian minister warned that the region faced the threat of Islamic State-inspired attacks designed to"glamorise terrorism".

About 100 Indonesian Islamic State supporters are believed to have returned home, but experts say no more than 15 saw combat.

"Until now, the people we have detained have been those arrested at the Syria-Turkey border," Nasution said. "So they haven't yet entered Syria, or they have come back, because they were disappointed with the conditions there."

Although few fighters have returned, Nasution said it did not take many battle-hardened militants to launch a major attack in Indonesia.

Jemaah Islamiyah, the Indonesia-based militant group responsible for most of the country's major attacks since the late 1990s, was founded by several dozen Indonesian and Malaysian militants who returned home after battling the Soviet Union in the Afghan jihad in the 1980s and early 1990s.

"Some people here have the intention to launch an attack, so if they have the chance, they will do it," Nasution said. "Our responsibility now is to minimize their chances."

Indonesia has stepped up security at foreign embassies in Jakarta in the wake of the attacks that killed 129 people in Paris last week, and Nasution said the country was beefing up security and surveillance in its provinces.