A Bangladesh court has sentenced to death 10 leaders and activists from a banned armed group for a plot in 2000 to kill Prime Minister Sheikh Hasina by planting bombs at one of her rallies.

Judge Mamtaz Begum sentenced the suspects on Sunday in the capital, Dhaka, and ordered them to be executed by firing squad, which is unusual in Bangladesh, where most executions take place by hanging.

Prosecutors said two bombs were found a day before Hasina was scheduled to address a rally at a college campus in the southern town of Kotalipara.

Those convicted belong to the Harkatul Jihad-al-Islami group. Defence attorneys said they would appeal the verdict.

The group's former chief, Mufti Abdul Hannan, was involved in the plot along with his associates, prosecutors told the court. Hannan was hanged in April for his involvement in a 2004 grenade attack on a British envoy in Bangladesh.

The court acquitted 10 of the suspects for lack of evidence, said prosecutor Khondaker Abdul Mannan.

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Harkatul Jihad-al-Islami has been blamed for many attacks in Bangladesh in recent years.

Though weakened, the group is struggling to fight the government's nationwide crackdown against those wanting to establish strict Islamic law in the Muslim-majority country.

Bangladesh has experienced a rise of armed groups in recent years. Scores of attacks have taken place against members of minority groups, foreigners and secular bloggers.

The Islamic State of Iraq and the Levant (ISIL, also known as ISIS) group has claimed responsibility for many of the attacks, but Hasina's government has rejected the claims.

Authorities say ISIL does not exist in Bangladesh and blame the attacks on a domestic group, Jumatul Mujahedin Bangladesh.

Hasina, who is in her second stint as Bangladesh's leader, was also prime minister from 1996 to 2001.