JAKARTA - A court in Indonesia has halved the sentence of a Muslim cleric who has been accused of leading the regional terrorist group Jemaah Islamiyah.

Abu Bakar Bashir has been serving a three-year sentence for immigration violations, but the Supreme Court Tuesday cut his sentence to 18 months. Bashir was arrested in October 2002, and with time served, is expected to be released later this month.

Although Bashir has been accused of leading Jemaah Islamiyah, he has never been charged with terrorist offenses. He denies that he has played any role in the terrorist actions Jemaah Islamyah is accused of carrying out, including the 2002 Bali bombing, which killed more than 200 people.

He was originally convicted and sentenced to four years in jail on charges of undermining the state and immigration violations. All but the immigration charges were cleared in the first round of his appeal, when his sentence was also reduced to three years.

Bashir's early release is sure to stir controversy and raise questions over Indonesia's commitment to fighting terrorism, but the country has otherwise established a strong record.

Three of the Bali bombers have been sentenced to death, and more than 25 others are serving long prison terms. Indonesia has come in for widespread criticism for what some people consider a lenient sentence for Bashir, but observers say the fault lay in a weak prosecution case.

One of Bashir's lawyers, Mahendradatta, says that despite the sentence cut, he believes that the sentence is too harsh for an immigration violation. The defense team will seek a judicial review of the sentence. "The lawyers will keep on fighting because we are sure that there is no grounds to give sentence to Abu Bakar Bashir," he says.

Bashir is the founder and principal of an Islamic boarding school on the Indonesian island of Java. At least five of the main players in the Bali bombing were graduates of Bashir's Al-Mukmin school.

Other graduates were involved in last year's bombing of the JW Marriott Hotel in Jakarta, in which 12 people died. Despite calls for the school to be shut down, the government has declined to take any action.

Jemaah Islamiyah says it is fighting to establish an Islamic state in Southeast Asia. Many of the group's members have ties to the al Qaida terror network.