New Delhi, Aug 25 - Buta Singh, chairman of the National Commission for the Scheduled Castes, Tuesday approached the Delhi High Court challenging the Central Bureau of Investigation's (CBI) notice to appear before it as a witness in a case of alleged bribery against his son.

His plea is likely to be heard Wednesday.

The CBI Monday issued the notice to Buta Singh to appear before it as a witness in the case of alleged bribery registered against his son Sarabjot alias Sweety Singh.

In his plea, Buta Singh has sought the CBI's notice be quashed, and has contended he held a constitutional post and the investigating agency has not sought permission before issuing him the notice.

On July 30, Sweety Singh was caught taking a bribe of Rs.1 crore (Rs.10 million) from Nashik-based contractor Ramraj Patil, in return for withdrawing a case of atrocities against the Scheduled Castes filed against him. He was brought to Mumbai the same night and subsequently arrested. He was later freed on bail.