Indonesian militant cleric Abu Bakar Bashir was jailed for 15 years on Thursday for his involvement with a group that aimed to kill the country's president.     

Jailing Bashir has been seen as an important step in the Indonesian government's efforts to weaken terror groups, but may not reduce the threat of attacks in the most populous Muslim country as others seek to push an Islamist agenda.     

Bashir does not command widespread support in Indonesia, but analysts have said a guilty verdict could inflame hardcore Islamists, some of whom have vowed reprisals after the US killing of Al Qaeda leader Osama bin Laden.

Underlining that risk, an anonymous text message circulating through the capital this week warned of 36 bombs exploding across the country the moment the judge in the south Jakarta court announced the verdict.

"The heavier the sentence will be the better, because it is another step to stem the radicalisation of more young people," Ansyaad Mbai, the head of the country's counter-terrorism agency, told Reuters.     

"If he is put behind bars it will not affect the security risk, but it is still better to keep him from preaching hate speeches."     

Police have stepped up security, with 2,900 officers at the court alone, where phone lines were scrambled and balaclava-wearing snipers took positions on surrounding buildings.

The frail 72-year-old cleric faced charges of supporting a paramilitary group that aimed to destabilise Southeast Asia's largest economy, and turn the officially pluralist and mostly moderate Muslim country into a state with Islamic law.

"Give me strength to fight against the infidels, Islam's enemies," said Bashir in a prayer at the court to hundreds of his followers, many of whom travelled from other cities for the conclusion of a long trial.     

"I don't think his conviction will have much impact one way or the other -- most of the small groups that have emerged over the last two years seem to be acting on their own initiative, not on the instruction of a single leader like Bashir," said Sidney Jones, senior adviser for the International Crisis Group in Jakarta, speaking before the verdict was announced. -Reuters