A Bangladesh court on Wednesday sentenced to death two Islamic militants for gunning down a police informant eight years ago, a prosecutor said.

A fast-track court handed down the sentences after earlier convicting the pair, both in their 20s and members of banned militant outfit Jamayetul Mujahideen Bangladesh (JMB), said prosecutor Taslima Yesmin.

Bangladesh's war crimes court Monday sentenced a former ruling party official to hang for mass murder, the 14th person convicted of atrocities during the 1971 independence struggle against Pakistan, a prosecutor said.

Mobarak Hossain, who was expelled from the Awami League after he was charged with war crimes in 2012, was found guilty of heading a militia that rounded up and killed scores during the nine-month conflict.

Suspected Islamic militants have hacked to death a university professor in western Bangladesh, several years after he led a push to ban students wearing full-face veils, police said Sunday.

Police have arrested at least 20 people for questioning over the murder near Rajshahi University in the west of the Muslim-majority country where the victim was a professor of sociology, a senior officer said.

Bangladesh's largest Islamist party faces an existential crisis after a series of body blows, including the sentencing to death of its leaders and abandonment by its main secular ally, say analysts.

While support for radical Islamists has surged in many Muslim majority countries of late, Jamaat-e-Islami has bucked the trend after failing to banish the taint of siding with Pakistan in Bangladesh's 1971 independence war.

Bangladesh's highest court Monday upheld the death sentence against a leader of the largest Islamist party after he was convicted of committing war crimes, including mass murder, during the 1971 independence conflict.

The Supreme Court's rejection of Mohammad Kamaruzzaman's appeal means that he will now be hanged within months, provided the case is not reviewed again or he is granted clemency by the country's president.

A media tycoon who is a key figure in Bangladesh's largest Islamist party was sentenced to death Sunday for war crimes, just days after its leader was ordered hanged for similar offences.

The war crimes court found wealthy businessman Mir Quasem Ali, an official of the Jamaat-e-Islami party, guilty of 10 charges including murder and abduction during Bangladesh's 1971 war of independence against Pakistan.

A massive nationwide power blackout hit Bangladesh on Saturday after a transmission line failed, leaving homes, businesses and shops in the densely-populated country without electricity.

Power was restored in some parts of the capital Dhaka after several hours, and authorities said they hoped to have electricity back on across the nation of 155 million by Saturday evening.

Islamists clashed with police in several Bangladesh cities on Thursday as part of a nationwide strike to protest against their leader being sentenced to death for war crimes, police said.

Officers fired rubber bullets and tear gas at rock-throwing protesters who tried to block several key highways in the northwestern cities of Bogra and Rajshahi, police officers told AFP.

A Bangladesh court on Wednesday sentenced to death the leader of the country's largest Islamist party for war crimes, a long-awaited verdict that triggered violent protests by his supporters.

The war crimes tribunal found Motiur Rahman Nizami, head of the Jamaat-e-Islami party, guilty of mass murder, rape and looting during Bangladesh's war of independence against Pakistan in 1971.

Bangladeshi war criminal Ghulam Azam, who was sentenced last year to 90 years in prison for masterminding atrocities during the country's 1971 independence war, died late Thursday aged 91.

Azam was the wartime head of Jamaat-e-Islami -- the country's largest Islamist party, later turning into its spiritual leader and a key player in the country's politics.