Police this evening arrested the developer of the promotional website of the mass protest to be held on December 23.
A police spokesperson said Ali Ahsan was arrested under a warrant in an ongoing investigation.
The police, however, declined to provide details of the investigation.
Police had launched an investigation into the death threats published on the promotional website.
Ahsan, who also serves as the editor of the online publication DhiIslam, was summoned to the police headquarters last evening to clarify who instructed him to develop the website and who published the information on it.
The police also confiscated the hard drive used by Ahsan for the website's development.
The slogans on the website included "the ruling of those who break the laws and challenge Islam is killing them by the public", "today's law is to kill anti-Islam activists… and those who support them" and "ready to kill anyone who challenge the religion of Islam without regarding his party".
The police yesterday summoned Adhaalath Party President Sheikh Imran Abdulla and Civil Coalition official Abdulla Mohamed over the death threats.
Hackers infiltrated the website yesterday and threatened the organisers of the protest by putting a message on its homepage saying, "we'll come out against you with machetes if you protest."