A Bangladeshi law student who posted against Islamism on his Facebook page has been murdered, police said Thursday, the latest in a a series of killings of secular activists and bloggers in the country.

"At least four assailants hacked Nazimuddin Samad's head with a machete on Wednesday night. As he fell down, one of them shot him with a pistol from close range. He died on the spot," deputy commissioner of Dhaka Metropolitan Police Syed Nurul Islam told AFP.

"It is a case of targeted killing. But no group has claimed responsibility," Islam said, adding police were investigating whether Samad was murdered for his writing.

The Dhaka Tribune said the assailants shouted Allahu Akbar (God is Greatest) as they attacked Samad on a busy road near Dhaka's Jagannath University, where he was a law student.

Samad had only recently arrived in Dhaka from the northeastern city of Sylhet to study law.

Deputy commissioner Islam said police suspect the attackers had been monitoring the victim since before he arrived in Dhaka.

Last year, suspected Islamist militants hacked to death at least four atheist bloggers and a secular publisher in a long-running series of targeting killings of anti-Islam activists in the Muslim majority country.

Police arrested members of a banned group called the Ansarullah Bangla Team over those murders, although none have yet been prosecuted.

Imran Sarker, who leads Bangladesh's largest online secular activist group, said Samad had joined nationwide protests in 2013 against top Islamist leaders accused of committing war crimes during the country's war of independence.

"He was a secular online activist and a loud voice against any social injustice. He was against Islamic fundamentalism," said Sarker, head of the Bangladesh Bloggers Association.

Samad had written against radical Islam in a number of recent Facebook postings.