Teams of Central Bureau of Investigation started conducting raids at the offices and residences of former chief minister of Haryana Om Prakash Chautala and his two sons Ajay and Abhay Chautala.
The raids are being conducted at 21 places in five states and Union territories namely Delhi, Haryana, Himachal Pradesh, Rajasthan and Chandigarh.
CBI has registered cases against the former chief minister for acquiring wealth beyond his known sources of income.
The sons of Chautala are also facing prosecution for the illegal appointment of the school teachers in another case.
Senior officials of the investigating agency refused to give more details.
"We would inform the media about the developments later in the day," an official of the organisation said.
The Chautalas were not available for comment.