Police said Amirul Chakdar, the president of the party's Nasirnagar Union unit, has been detained in the wee hours of Wednesday from his home.
"There are allegations of his direct involvement," said Nasirnagar police OC Md Abu Zafar.
At least 15 temples and more than a hundred homes were vandalised and looted on Oct 30 at Nasirnagar over a Facebook post ‘insulting’ Islam.
bdnews24.com investigations revealed that local turf war between Nasirnagar MP and Fisheries Minister Muhammed Sayedul Hoque and Brahmanbarhia district unit AL President and MP Obaidul Muktadir Chowdhury had led to the attacks.
"There is a feud among leaders of a political party in that area. We think the attacks might have been triggered by it, but it needs to be further investigated," Chittagong Range Additional DIG Md Shawkat Hossain told bdnews24.com on Monday.
Hossain headed the probe committee.
On Tuesday, the BNP said the report was 'false and fabricated'.
Its senior leader Ruhul Kabir Rizvi claimed that two local BNP leaders were blamed in the report as responsible along with 18 Awami League leaders.
According to him, it was an attempt to save police and local Awami League MPs, who he claimed, were behind the attacks.
On Nov 13, unidentified attackers set fire to fishing nets in a house of a Hindu fisherman.
Three cases have been initiated over the incidents. Police have announced Tk 100,000 reward for information leading to the arrest of the perpetrators.
As many as 85 people have been arrested until Tuesday over the mayhem, police said.