Two people, including the editor of a magazine for the transgender community, have been hacked to death in the capital of Bangladesh.
A third person, a security guard at the apartment building where the killings took place, was seriously wounded in Monday's attack in Dhaka, in which six attackers murdered Xulhaz Mannan and Mahbub Tonoy.
Mannan was the editor of Rupban, the only LGBT magazine in the country.
"Unidentified attackers entered an apartment at Kalabagan and hacked two people to death," Maruf Hossain Sardar, a Dhaka Metropolitan Police spokesman, told the AFP news agency.
No suspects have been arrested, police officer Shamim Ahmed told the Associated Press news agency.
Prime Minister Sheikh Hasina Hasina vowed to hunt down and prosecute those responsible.
She accused the country's opposition party and what she called allied armed groups of being behind the killings. The opposition has denied the allegations.
"The BNP-Jamaat nexus has been engaged in such secret and heinous murders in various forms to destabilise the country," Hasina said, referring to the opposition Bangladesh Nationalist party and the outlawed Jamaat-e-Islami party.
"Such killings are being staged in a planned way."
But the BNP called Hasina’s accusations "ridiculous and unfortunate.
"How can the government come to the conclusion without any proper investigation?" Mirza Fakhrul Islam Alamgir, the secretary general, told Al Jazeera.
"Instead of finding the murderers, the government is busy accusing the democratic opposition," he said, adding that the government has failed to investigate a spate of recent killings.
Alamgir said that govermnment repression of opposition has shrunk the democratic space and the extremists are taking advantage of that.
Ansar al-Islam claim
A group affiliated to al-Qaeda later claimed responsibility, the Reuters news agency has reported.
A Twitter account associated with the Ansar al-Islam group said its members had killed the men, denouncing them as "the pioneers of practicing (sic) and promoting homosexuality in Bangladesh."
Ansar al-Islam has issued similar claims in the past, according to a Bangladeshi security expert. The authenticity of the claim of responsibility could not immediately be verified.
Maruf Hossain Sardar, a spokesman for Dhaka city police, dismissed the group's claim as baseless, saying international armed groups such as the Islamic State of Iraq and the Levant and al-Qaeda had no organisational base in Bangladesh.
Mannan's magazine, Roopbaan, was launched two years ago and became a platform for promoting the rights of LGBT people in a country where homosexuality is illegal.
The group also runs an annual Rainbow Rally parade on Bengali new year, that was cancelled this year owing to security concerns.
The incident came two days after a university professor was killed in similar fashion in an attack in Rajshahi, which was claimed by the Islamic State of Iraq and the Levant (ISIL, or ISIS) group.
Mollah, a security guard, was wounded in the attack and is being treated in hospital [Mahmud Hossain Opu/Al Jazeera]
Parvez Mollah, an 18-year-old security guard, told Al Jazeera that the six attackers were aged between 25 and 30 and that they had arrived at the building posing as couriers.
"They told me they had some parcels for Mannan and, as I went up to his apartment, three of the six attackers followed me to the second floor and attacked Mannan with machetes," Mollah said.
"As Mannan fell to the floor, the attackers entered the apartment and fired bullets before fleeing."
Al Jazeera's Tanvir Chowdhury, reporting from Dhaka, said that freedom of speech was threatened by such attacks.
OPINION: The hit list - endangered bloggers of Bangladesh
"There is widespread fear in the country and the government is denying involvement of international terrorists or ISIL, even after such groups have announced that Bangladesh is one of their operating bases," he said.
Earlier this month, Nazimuddin Samad, a 28-year-old law student, was hacked to death by three men riding a motorcycle as he walked with a friend in central Dhaka.
Last year, at least four atheist bloggers and a secular publisher were hacked to death in a long-running series of killings of secular activists.
The South Asian country has seen a surge in violent attacks over the past few months in which liberal and secular activists, members of minority Muslim sects and other religious groups have been targeted.
With additional reporting by Mahmud Hossain Opu
Source: Al Jazeera and agencies