Military-led joint forces in emergency-ruled Bangladesh arrested former prime minister Khaleda Zia's younger son in overnight raids, 46 days after her influential eldest son was taken into custody, officials said on Monday.

Arafat Rahman Koko was arrested from his mother's Dhaka Cantonment residence after midnight on Sunday. "He has been taken to custody," a security official said without elaborating.

Joint military and police forces carried out a massive search inside the house while senior officials talked to Zia and her son for a 'long time' before taking him to custody, private ATN Bangla television and the Prothom Alo newspaper reported.

Security officials said after 'primary interrogations,' Koko could be brought to court early Tuesday to seek a magistrate order to send him to jail or bring him to remand for further interrogation.

Meanwhile, communication adviser of the interim cabinet, retired major general Abdul Matin told media persons that a task force will investigate allegations against Koko.

"I do not know yet what allegations he is facing. But there must be some specific allegations," said Matin, also the head of a national task force against severe crimes and corruptions.

The arrest of Koko, a low-profile businessman, came 46 days after his high-profile elder brother Tarique Rahman was arrested from the same house in a similar pre-dawn raid and remanded into custody for several days for interrogation on graft and extortion charges.

Newspapers earlier said the movement of Khaleda Zia outside her residence was restricted and leaders of her Bangladesh Nationalist Party were barred from meeting her since last week.

Security officials last month searched Koko's advertising firm Adsign and arrested one of his partners from the office on graft charges as part of the ongoing anti-corruption campaign.

Koko also owns several other companies and passenger ferries. His elder broether Tarique Rahman now awaits trial at an ordinary prison ward of Dhaka Central Jail. Legal experts said he could be imprisoned for five years if convicted.

Nearly 60 high profile politicians, mostly belonging to BNP, have been arrested as part of a massive anti-corruption campaign after Bangladesh's reconstituted interim government of chief adviser Fakhruddin Ahmed took over a day after Bangladesh came under emergency rule on January 11.