DHAKA (AFP) - Security was tight in the Bangladeshi capital on Thursday as a top court was set to rule on whether to ban the nation's biggest Islamic party, with fears the verdict could trigger fresh unrest.

The High Court was scheduled to announce its decision on the legality of Jamaat-e-Islami after a petition was lodged arguing the party's charter conflicted with the nation's secular constitution.

The decision could trigger fresh protests by Jamaat supporters in the politically volatile country, already reeling from deadly violence over war crime verdicts passed on Jamaat's top leadership.

Police officers and members of the elite Rapid Action Battalion have been deployed outside the court in central Dhaka ahead of the verdict in an attempt to prevent any violence.

"We have taken adequate security measures in and around the court area," deputy commissioner of Dhaka Metropolitan Police Maruf Hossain Sarder told AFP.

A leading Sufi group, which practices Islamic mysticism, and dozens of others filed the public interest litigation in January 2009 seeking to scrap Jamaat's registration just days after a secular government took power.

A lawyer for the petitioner, Sheikh Rafiqul Islam, told AFP on Wednesday that Jamaat's charter violates the secular constitution as it calls for the rule of Allah and discriminates against minorities and women.

"If the court cancels Jamaat's registration, it cannot take part in any polls under the country's current election rules," Islam said.

Defence lawyer Tazul Islam said no clause of the party charter was in conflict with the constitution.

"If they scrap Jamaat's registration, 28 more parties will also face the same fate automatically," he said.

Secular protesters have long demanded that Jamaat be banned for its role in the 1971 war of independence, during which it opposed Bangladesh's break away from Pakistan.

Top Jamaat leaders are being tried for crimes during the war and four of them have been sentenced to death for murder, mass murder, rape and religious persecution during the struggle.

Protests over the verdicts have sparked violence that has left at least 150 people dead during street clashes with security forces, Human Rights Watch said in a report released Thursday.

Jamaat says the trials are a sham aimed at eliminating the party, which is a key opposition force.

Abdullah Taher, a senior Jamaat official, declined to comment on the case ahead of the High Court's judgement, but accused the government of "persecuting" the party which has millions of loyal supporters.

"About 50,000 of our leaders and activists have been arrested since the first war crime verdict against our leaders," he told AFP, adding that police have also filed cases against some half a million of its supporters.

About 90 percent of Bangladesh's 153 million strong population are Muslim and the constitution was changed in 1988 making Islam the nation's state religion.

But the original constitution, drafted by the main secular party after independence, bars the use of religion in politics.