Bangladeshi anti-crime elite force Rapid Action Battalion (RAB) arrested the main suspect connecting with the murder of writer blogger Avijit Roy, a press release of the RAB said Monday.

The suspect identified as blogger Shafiur Rahman Farabi was arrested from Jatrabaria area in the capital. After the arrest he was taken to RAB headquarters at Uttara and then he was handed to detective branch.

Avijit Roy, 42, a U.S. citizen of Bangladeshi origin was hacked to death by two attackers wielding machetes in Bangladesh's capital city of Dhaka Thursday evening, when he was leaving a book fair with his wife, who was also wounded seriously in the attack.

His death created concern locally and internationally. The United Nations and the United States expressed sorrow at the death of Roy. The United States on Friday slammed the killing of Avijit, offering help in the investigation.

Bangladesh government agreed to accept the assistance.

Bangladesh Foreign Minister AH Mahmood Ali said Dhaka has decided to seek FBI's assistance in the Avijit murder probe.

The foreign minister conveyed the government decision to a group of top diplomats from influential countries at the state guest house on Sunday.

Avijit was an engineer by profession, but had reportedly received death threats from Islamists for his articles advocating secularism.

Avijit's blogging had reportedly evoked the ire of Islamist fundamentalists and he was regularly threatened by unknown assailants.