Dhaka: Condemning the killing of publisher Faisal Arefin Dipan and the continued violence against the online community the United Nations said the perpetrators must be brought to justice.

The UN, in a statement from Bangladesh office on Saturday night, said this murder and the violent assaults on Ahmedur Rashid Tutul, Tariq Rahim, and Ranadipan Basu are unacceptable attacks aimed to intimidate and restrict the right of individuals to express themselves freely.

The UN Resident Coordinator in Bangladesh Robert D Watkins said these killings must be condemned at all levels of political and religious leadership in order to prevent further attacks.  

‘The perpetrators must also be brought to justice and the authorities need to provide immediate protection to citizens thought to be at risk,’ he added.

Ahmed Rahim Tutul, publisher of the books of slain writer and blogger Avijit Roy, and two bloggers and writers Sudeep Kumar Roy Barman alias Ranadeep Basu and Tareque Rahim were stabbed by some unidentified miscreants in the city’s Lalmatia area on Saturday.

Hours later, Avijit’s another publisher Faisal Arefin Dipan, 45, publisher of Jagriti publication house, and son of former professor of Dhaka University's Bangla department Abul Kashem Fazlul Haq, was stabbed to death by miscreants on the second floor of Aziz Super Market in the city's Shahbagh area.   

Fears of Islamist violence have been rising in Muslim-majority Bangladesh after four atheist bloggers were murdered this year, allegedly by Islamist hardliners.

Al-Qaeda in the Indian Subcontinent (AQIS) claimed responsibility for Saturday’s attacks, along with the four earlier ones, branding the victims ‘blasphemers’ and warning any writers who criticiseIslam of being next in line.

Dipan published several books by Avijit Roy, a US national of Bangladeshi origin, who was hacked to death outside a book fair in February in the capital.

Shuddhaswar owner Ahmedur Rashid Tutul, 43, whose condition is still serious, also previously brought out several of Roy’s books including one on homosexuality.

‘It’s a failure of the government that it has not been able to prosecute the killers,’ said Imran Sarker, head of a secular bloggers’ group, which organised the protests.

‘There is a climate of impunity in which these militants now operate brazenly,’ he said.

Police said both of Saturday’s attacks bore the hallmarks of the earlier ones on bloggers which were blamed on banned local group Ansarullah Bangla Team. Police could not confirm if AQIS was behind the latest ones.

Bloggers say about a dozen secular writers have fled the country in fear following this year’s killings, while some have faced threats themselves from Islamists.

Criminals have targeted secularist writers in Bangladesh in recent years, as the government has cracked down on Islamist groups seeking to turn the South Asian nation of 160 million people into a sharia-based state.

Four secular bloggers have been hacked to death this year for writing critically about Islamist militancy.

At least 15 members of an al Qaeda inspired group Ansarullah Bangla Team, including a British citizen, have been arrested since August, after blogger Niloy Chatterjee was killed by a group of attackers armed with machetes.

The country has also been rocked by attacks in which two foreigners were shot dead and a Shi'ite shrine in Dhaka was bombed.

Prime Minister Sheikh Hasina’s government has blamed local hardline Islamist groups for the earlier attacks and launched a crackdown after facing Western criticism of failing to stop the bloodshed.

Bangladesh has also been rocked by the recent murders of an Italian aid worker and a Japanese farmer, while Dhaka’s main Shiite shrine was bombed last weekend, killing two people and wounded dozens.

The government has accused its political opponents of orchestrating those attacks to destabilise the country, rejecting the Islamic State group’s claim of responsibility.

Bangladesh prides itself on being a mainly moderate Muslim nation, but the gruesome killings along with the Shiite shrine bombing have heightened fears for minorities.