A Bangladesh court sentenced 10 militants to death on Sunday over a failed plot to assassinate Prime Minister Sheikh Hasina by detonating a huge bomb at one of her rallies in 2000.

"The men were sentenced to death by a firing squad for planting a huge explosive near where Hasina was scheduled to speak during her first term as prime minister in 2000," prosecutor Shamsul Haq Badol told AFP.

“The bomb was planted in an attempt to kill Sheikh Hasina, high-ranking leaders of the (ruling) Awami League party and dignitaries,” Badol said.

The 76-kilogram explosive was detected and defused, sparking a manhunt for those responsible for the assassination attempt on Hasina, who is now in her third term as leader of Bangladesh's government.

Police allege the operation was led by Mufti Abdul Hannan, the late leader of extremist group Harakat ul Jihad Al Islami, which perpetrated a string of attacks across Bangladesh in the late 1990s and early 2000s.

Hannan, the main accused in the failed bomb plot, was hanged in April for orchestrating a grenade attack on Britain's envoy to Bangladesh in 2004.

The accused in this latest case wanted to kill Hasina because “they said she was not a Muslim, and an agent of India, and Islam can be established (in Bangladesh) only by killing her,” Badol claimed.

He said another large explosive was found three days later at a helipad where Hasina was scheduled to land.

A separate prosecutor, Khandaker Abdul Mannan, said those sentenced to death were also implicated in other assaults, including a deadly bombing at a church and a secular festival.

Defence lawyer Faruque Ahmed said the defendants would lodge an appeal through the jail authorities.

“There are a lot of questions about this case. The defendants said they did not get justice,” he told AFP. Hannan tried to kill Hasina in a separate grenade attack at a rally in the capital Dhaka in August 2004, in which 22 people were killed, Badol said.

Hasina, who was the opposition leader at that time, suffered injuries to her ear in the carnage.

A madrasa teacher who studied in India and Pakistan, Hannan fought against the Soviets in Afghanistan before returning home to Bangladesh where he rose to prominence for a string of deadly attacks under his command.