The Anti-Corruption Commission (ACC) has asked all banks to provide information on the bank accounts of two public works department's former officials and their families by October 27.
They are ex-chief engineer Md Rafiqul Islam and former additional chief engineer Md Abdul Hie.
In a letter to all the banks issued on Thursday, the ACC also sought details about the bank accounts of Rafiqul's wife Rashida Islam, father Abdul Hamid, mother Hirna Khatun and son Khaled Mainul Islam.
The ACC also directed the banks to provide the bank accounts' information of Abdul Hie's wife Bonani Sultana Kona, his father Selim Uddin and mother Khodeja Begum.
On Wednesday, the ACC imposed travel ban on 22 persons, including Rafiqul and Abdul Hie, because of their alleged involvement in the casino business and accumulation of illegal wealth.
Earlier, the National Board of Revenue had sought their bank accounts' information.