DHAKA - A Bangladesh court on Wednesday sentenced 19 people to death over a 2004 grenade attack on the current prime minister, although a top opposition leader escaped with a life sentence.

The opposition staged protests and slammed the sentences as “political vengeance” as police went on high alert across the South Asian country, with a bus in the north allegedly fire-bombed.

The 2004 attack in Dhaka on a rally by Sheikh Hasina, at the time in the opposition and now prime minister, left her injured and killed 20 people.

Tarique Rahman, son of then-premier and Hasina’s ally-turned-archrival Khaleda Zia, was among 49 people on trial, with Rahman charged with criminal conspiracy and multiple counts of murder.

Rahman, 50, was however tried in absentia after he fled the country for London in 2008. He now leads the main opposition Bangladesh Nationalist Party (BNP) from exile after Zia was jailed in February for five years for corruption. “Does politics mean attacking the opposition?” judge Shahed Nur Uddin said over a portable loudhailer as he first read out the verdict and then handed down the sentences. “We thank God for the verdict,” prosecutor Mosharraf Hossain told reporters. “We hoped that Tarique Rahman would get the death sentence,” he said, adding the court observed that Rahman played a key role in the attack.

Hossain said two former ministers including a powerful ex-home minister and two former heads of the country’s powerful intelligence agencies were among others handed the death sentence. A total of 15 Islamist extremists from the banned Harkat-ul Jihad al Islami (HuJI), whose leader was executed in April last year with two others, were also sentenced to death for planning and carrying out the attack.

Prosecutors said former BNP minister Abdus Salam Pintu colluded with HuJI and handed over grenades for the attack. Hasina was addressing the rally when the grenades exploded and suffered severe injuries in one ear. Among the dead was the wife of a former president.

Four years later, Hasina stormed back to power after leading a secular coalition to a landslide victory in elections in December 2008.

Death sentences are common in Bangladesh, with hundreds of people on death row. All executions are by hanging, a legacy of the British colonial era.

At least nine top Islamist extremists, five leaders of the country’s largest Islamist party and a senior opposition leader have been hanged since 2007.

Home Minister Asaduzzman Khan said justice had been done. But Rahman’s lawyer Sanaullah Mia said the charges were politically motivated. He questioned the timing of the verdict, saying it was aimed at keeping Rahman out of elections expected for December.

“There was no evidence or witness against him. No witness could say that conspiracy was hatched at Hawa Bhaban,” he told AFP, referring to a former BNP office used by Rahman.

Convicted former home minister Lutfozzaman Babar told AFP that his death sentence was “completely unjst” and that he was punished for refusing to testify against Zia and her son. “Allah knows it’s injustice,” he said. BNP spokesman Fakhrul Islam Alamgir called the verdict “a naked display of political vengeance”.

BNP activists staged protests in the capital Dhaka and at several towns across the country, moments after news of the verdict spread.

Two people were injured as a motor biker allegedly fire-bombed a public bus in the northern town of Shahjahanpur. Shahjahanpur police chief Latiful Islam said an alleged BNP youth wing activist was arrested for the attack. “He was trying to create anarchy,” he said.

Police commissioner Asaduzzaman Mia said police were on high alert across the country and would do “whatever is needed to provide safety to the people”.

“No anarchy will be tolerated,” he said.

Zia was transferred to hospital last weekend from the 19th-century Dhaka Central Jail, where she is the only prisoner. She has been on trial in a special room of the prison on additional graft charges that her supporters say are politically motivated.