Police arrested BNP's UK unit joint general secretary Shohidul Islam Mamun from his residence in Sylhet city's Badambagich on Monday afternoon, reports UNB.
Based on allegations, the law enforcers arrested him from his residence, said Md Abdul Wahab, additional deputy commissioner (Media) of Sylhet Metropolitan Police (SMP).
The police officer, however, denied disclosing the matter.
Meanwhile, SMP officials said the secretary might have been detained for his involvement with the attack on Bangladesh High Commission in the UK.
Earlier on 8 February, some leaders and activists of Bangladesh Nationalist Party (BNP) attacked Bangladesh High Commission in the UK as its officials refused to accept a memorandum regarding Zia Orphanage Trust graft case.