A key suspect and his accomplice accused of fanning communal hatred on social media and instigating the recent violence against the minority Hindu community in Bangladesh have confessed to their crime in a pre-trial hearing, a court official has said.

Shaikat Mandal confessed before a magistrate on Sunday that it was his Facebook post that led to the violence in Rangpur, Pirganj sub-district on October 17 during Durga Puja festivities in the country.

Mandal's accomplice Rabiul Islam is a 36-year-old cleric, who has been accused of arson and looting.

Shaikat Mandal and his accomplice Rabiul Isam have admitted their role before a senior judicial magistrate Delwar Hossain in (north-western) Rangpur, the court official told newsmen.

They were arrested from Gazipur on Friday in a police raid and booked under the Digital Security Act.

Mandal is a philosophy department student of Rangpur's Carmichael College and was expelled from the ruling Awami League's student wing Chhatra League after his arrest.

He had uploaded objectionable content on Facebook to boost his follower count, a Rapid Action Battalion (RAB) official was quoted as saying in a bdnews24.com report.

Islam helped Mandal instigate Muslims in the village through announcements on the loudspeaker on Friday, the official added.

Police officials claimed that the violence was instigated after a rumour began doing the rounds in Pirganj that a Hindu man had posted religiously offensive content on Facebook, the report said.

According to the police, around 70 Hindu homes were torched during the mayhem that ensued on October 17.

At least seven people have confessed to their crime under the pre-trial legal proceedings so far, with 683 arrests and more than 70 cases being filed accusing 24,000 suspects, most of whom were anonymous, media reports said.

Attacks on Hindus have been reported in Bangladesh during the Durga Puja festivities after an alleged blasphemous post on social media went viral on October 13.

Apart from Mandal and Islam, police also have under custody, Iqbal Hossain, who had allegedly placed the Quran at a Durga Puja venue in Cumilla, and Fayez Ahmed, who had posted a video of the Quran at the Puja venue, RAB officials said.

On Saturday, members of minority religious communities staged a mass hunger and sit-in demonstration at central Dhaka's Shabagh area and other parts of the country under the banner of the Bangladesh Hindu-Buddhist-Christian Unity Council.

The attacks on the Hindus in Bangladesh have been widely condemned by the United Nations.

Last week, Bangladesh Prime Minister Sheikh Hasina instructed her Home Minister to initiate immediate action against those who incited violence using religion as she asked people not to trust anything on social media without fact-checking.

Hindus constitute around 10 per cent of the Muslim-majority Bangladesh's 169 million population.