- People in United Kingdom, Germany and United States among those threatened
- Advocacy group calls it "an unacceptable attack on freedom of expression"
- Four secular bloggers have been brutally killed in Bangladesh this year
(CNN)Islamic extremists in Bangladesh appear to be taking their war on secular writers and bloggers beyond the South Asian country's borders.
A hit list purporting to be from the militant group Ansarullah Bangla Team has been sent out threatening people in Europe and North America.
"Let Bangladesh revoke the citizenship of these enemies of Islam," a statement accompanying the list says. "If not, we will hunt them down in whatever part of God's world we find them and kill them right there."
The list contains nine people in the United Kingdom, eight in Germany, two in the United States, one in Canada and one in Sweden. CNN isn't reporting any of the names on the list.
'An unacceptable attack on freedom of expression'
The demand to revoke their Bangladeshi citizenship doesn't make sense in all the cases, as some of those mentioned don't have it.
But the menacing language is deeply troubling in a year in which at least four bloggers have been hacked to death in Bangladesh after posting articles critical of Islam online.
"This international threat to writers and bloggers is an unacceptable attack on freedom of expression," said Thomas Hughes, the executive director of Article 19, a group that defends bloggers' rights worldwide. "Such threats often have a chilling effect on expression, encouraging individuals and organizations to self-censor for fear of violent reprisal."
People on previous list attacked
Islamist militants in Bangladesh have posted a hit list of writers they view as opponents of Islam before -- and acted on it.
Late last year, Reporters Without Borders said that a group calling itself Ansar al Islam Bangladesh published a list of writers it saw as opposing Islam.
Months later, blogger Asif Mohiuddin, whose name was on the list, said that at least nine of those on it had been killed and many others attacked.
Last month, police in Bangladesh arrested three suspected members of Ansarullah Bangla Team, one of them a British citizen, in connection with the killings of Avijit Roy and Anant Bijoy Das, two of the prominent bloggers attacked this year.
'One of the most active terror groups'
Dr. Ajit Kumar Singh, a research fellow at the South Asia Terror Portal in New Delhi, said last month that Ansarullah Bangla Team, more commonly known as Ansar Bangla, is a terrorist group that emerged recently.
It is believed to be linked to al Qaeda in the Indian Subcontinent, or AQIS, a branch of the international terrorist network that formed in recent years, he said.
Ansar Bangla is "one of the most active terror groups in Bangladesh now," and has been officially banned by the government there, he added.
"There is a battle going on in Bangladesh between fundamentalists and secularists," Singh said. "A blogger like Niloy Neel, the last one who was killed, was openly questioning fundamentalist thought. Organizations like Ansar Bangla wanted to shut him up -- and scare others into not talking."
Imran Sarker, president of the Blogger and Online Activists' Network in Bangladesh, said the struggle between hardliners and free thinkers began in early 2013, "when the liberal bloggers got united and started a movement against radicalization of the society by the militant groups.
Four shocking killings
The brutal killings of the four bloggers this year have shocked many people in Bangladesh and beyond.
In February, Roy, a Bangladesh-born American blogger, was killed with machetes and knives as he walked back from a book fair in Dhaka.
A month later, Washiqur Rahman, 27, was savaged by two men with knives and meat cleavers just outside his house as he headed to work at a travel agency in the capital.
Das, 32, was set upon with cleavers and machetes in May as he left his home on his way to work at a bank in northeastern Bangladesh. And less than two weeks ago, Neel was hacked to death in his Dhaka apartment.
Activists have criticized the initial response from Bangladeshi authorities to the killings.