DHAKA: A Bangladesh court sentenced two students to death on Thursday for the 2013 murder of a secular blogger, delivering the first convictions over a series of brutal killings that have rocked the Muslim-majority nation.

Ahmed Rajib Haider, 35, was hacked to death by machete-wielding attackers in February 2013, in the first of a string of attacks targeting secular writers.

The judge in the fast-track court on Thursday found both students and one other man, Maksudul Hasan, guilty of murder and convicted another five people on lesser charges related to Haider's death.

Hasan, 23, was given a life sentence.

One of the two students, who attended one of the country's top universities, is on the run and was sentenced in absentia.

"Two students of North South University, Faisal bin Nayem and Rezwanul Azad Rana, were sentenced to death. Rana has been a fugitive since the trial began," prosecutor Mahbubur Rahman told AFP.

Rahman said the two students had been "inspired" by the sermons of firebrand cleric Jashim Uddin Rahmani, 45, who was given five years in prison for abetting the murder.

"I am not satisfied. The judge said it was a pre-planned murder. They should have been given harsher punishments," he added.

Five more secular bloggers and a publisher have been brutally killed this year, triggering protests and claims that the government is not doing enough to protect dissident writers and activists.

Police say the banned Islamist group Ansarullah Bangla Team (ABT) was behind the attacks.

Related: Islamist group banned in Bangladesh after blogger killings

Haider, an architect, became a target of the group after he helped launch a massive protest against the leaders of the largest Islamist party, several of whom are accused of war crimes during Bangladesh's 1971 independence struggle against Pakistan.

Police said Haider had angered the students by writing against Islam and mocking the Prophet Mohammed on blog sites.

They said Rahmani, an ABT leader, had ordered the murders of other secular bloggers from jail while he was being tried for Haider's murder.

These include Avijit Roy, a US citizen of Bangladeshi origin who moderated an anti-religion website. He was killed in February.

Rahmani had preached that it was legal to kill atheist bloggers who campaigned against Islam, police said.

- Growing danger -

Haider's father said the sentences against some of those convicted were too lenient.

"I am not happy. These people are self-declared killers of my son. Yet not all of them got a death sentence," Nijam Uddin told AFP.

However, a lawyer for the defendants said they would appeal the verdict.

"In his verdict, the judge admitted there was no eye-witness to the murder. There was no way the two should get death penalty," Faruque Ahmed told AFP.

Secular groups have called nationwide protests and rallies to demand more protection for publishers, bloggers and writers, some of whom have fled the country or gone into hiding.

Several foreigners have also been murdered in recent months in Bangladesh, which has also suffered attacks on minority Sufi and Shia Muslims.

A long-running political crisis in the majority Sunni Muslim but officially secular country has radicalised opponents of the government and analysts say Islamist extremists pose a growing danger.

Haider was the first secular blogger to be murdered in Bangladesh. After his death, the country's Islamist parties began to protest against other campaigning bloggers, accusing them of blasphemy and calling for their execution.

The secular government of Prime Minister Sheikh Hasina reacted by arresting four bloggers including one who was allegedly attacked by the same group of students accused of Haider's murder.

The government also blocked about a dozen websites and blogs to stem the furore, as well as stepping up security for the bloggers.