AKARTA, Feb. 3 — A new militant Islamic militia has emerged here, according to a report released Tuesday by the International Crisis Group, just as Attorney General John Ashcroft is scheduled to arrive to address a conference on terrorism.

The new group, Mujahedeen Kompak, was formed by hard-liners who split from Jemaah Islamiyah, considered Al Qaeda's affiliate in Southeast Asia, according to the report, which was written by Sidney Jones, widely considered the leading authority on Jemaah Islamiyah. Kompak, an acronym, translates roughly as Action Committee for Crisis Response.

The emergence of the group in central Sulawesi Province, which has been racked by Christian-Muslim violence, "suggests a need to revise assessments about the nature and gravity of the terrorist threat in Indonesia," Ms. Jones wrote in the report. "While the shorter-term prospects are somewhat encouraging, there is an underappreciated longer security risk."

The organization presents a possible new partner for Al Qaeda, she wrote.

This is the sixth report about Jemaah Islamiyah and terrorism in Southeast Asia by Ms. Jones, an American who speaks fluent Bahasa Indonesia, the national language. American, Australian and Asian intelligence and police officials are in general agreement that she has done a better job of understanding and analyzing the organization than have their own agencies.

One of the most arresting facts in the 41-page report is contained in a footnote that establishes the date of the founding of Jemaah Islamiyah as Jan. 1, 1993. That comes from a document Ms. Jones obtained. It will surely be uncomfortable for many Indonesians, including senior government officials and religious leaders, who continue to insist that Jemaah Islamiyah does not exist.

Mr. Ashcroft is scheduled to speak Wednesday morning at the terrorism conference, which is being held in Bali and is jointly sponsored by Indonesia and Australia. He is hoping to meet with the Indonesian president, Megawati Sukarnoputri, in the afternoon, American and Indonesian officials said.

High on Indonesia's agenda will be a request that the United States turn over a top Jemaah Islamiyah operative, Riudan Isamuddin, better known as Hambali, a senior Indonesian official said. After an intensive manhunt, Mr. Isamuddin, an Indonesian who was one of the few non-Arabs to earn a place in Osama bin Laden's inner circle, was captured by the Central Intelligence Agency in Bangkok in August. He is being interrogated at an undisclosed location, and the United States has resisted persistent entreaties from the Indonesians for access to him.

The Federal Bureau of Investigation has had a team, or teams, of agents in Indonesia since August 2002, when two Americans were killed and eight were wounded in an attack in the easternmost Indonesian province of Irian Jaya. The attacks were in an area owned by Freeport-McMoran Copper and Gold Inc., the giant mining company, which had paid Indonesian soldiers to provide security. More F.B.I. agents came two months later, after the car bomb attacks that killed more than 200 in Bali.

Publicly, American officials say the Indonesians have been cooperating with the F.B.I. in those investigations. Privately, however, American officials complain about the lack of full cooperation.

All indications are that Indonesian soldiers were involved in the killings in Irian Jaya, American officials have said. Because of a lack of full cooperation and the absence of vital forensic evidence, however, they are doubtful that the killers will ever be found.

In the attacks in Bali, the Indonesian government has not given the F.B.I. as much direct access as it would like to those under arrest, several of whom have been convicted and are facing execution, officials said. The officials added that this was not considered a serious impediment, because, they noted, the Indonesians had done a good job of rounding up and prosecuting the attackers.

The arrests have seriously crippled Jemaah Islamiyah, which has also been weakened by internal divisions "over how, when and where to wage jihad," Ms. Jones said in her report.

A top priority for governments now, she concluded, is to prevent central Sulawesi from becoming an international training center like Afghanistan was under the Taliban.