Sources said Mamun, now on a five-day remand in an arms case, is being quizzed extensively about his involvement in unbridled corruption through which he amassed huge money and wealth.

They however declined to divulge any information received from him during interrogation.

The interrogators also questioned Mamun about how he had collected the pistol and bullets recovered during Monday's raid at his Banani DOHS house. They wanted to know from him about a huge cache of firearms and ammunition that his cohorts are suspected to have in their possession, the sources said.

Mamun remained mum when questioned about the arms and ammunition, said one source seeking anonymity.

Police said Mamun, listed by the Anti-Corruption Commission (ACC) as a top graft suspect, was arrested on Monday raiding his house.

But different national dailies had earlier reported that Rapid Action Battalion (Rab) personnel caught Mamun from a house at Naya Paltan in the capital on January 31.