The Anti-Corruption Branch (ACB) has written to the Lieutenant Governor's Secretariat demanding that Amanatullah Khan be removed as the Delhi Waqf Board chairman for allegedly hampering a probe by "bullying" witnesses in a case against him, sources at the LG office said on Wednesday.

Khan, who is also the Aam Aadmi Party (AAP) MLA from Okhla, expressed faith in the judiciary and Constitution and charged that Prime Minister Narendra Modi was scared of the party supremo Arvind Kejriwal and targeting to harass them.

"Modiji is scared of Arvind Kejriwal ji and constantly targeting his companions to harass them whether Manish Sisodia, Satyendar Jain or myself but let Modiji know we are not going to be scared. We have complete faith in the judiciary and Constitution," Khan tweeted in Hindi.

The ACB said Khan's "criminal and bullying nature" was scaring witnesses in the corruption case to come forward for recording their statements, according to the LG office sources.

"People are afraid of Amanatullah Khan because of his bullying nature and past record which is preventing witnesses to make statement against him freely and fairly. Therefore, fair investigation can't be conducted in this case as long as Khan continues to hold the office of Chairman of Delhi Waqf Board," a source said, quoting a letter written to the LG office by the ACB.

The ACB has sought the removal of Khan till the probe was completed, they said.

The letter, written recently to the LG Secretariat by S K Gautam, the then Special Commissioner of Police (ACB), said the witnesses in the case are afraid of Khan due to his "aggressive behaviour" and his position in the Delhi Waqf Board.

The case against Khan relates to "financial bungling" in the bank accounts of the Waqf Board, creation of tenancy in Waqf Board properties, "corruption" in purchase of vehicles and "illegal appointment" of 33 people in the Delhi Waqf Board in violation of the service rules, among others, the sources said.

A case in this regard was registered by the ACB in January 2020 under various provisions of the Prevention of Corruption Act and the Indian Penal Code.

The ACB cited 23 criminal cases were registered against Khan out of which two were pending trial, seven are pending investigation at various police stations including one with the CBI.

"The ACB letter comes in the wake of a report submitted by the investigating officer in the case citing threats from Khan to the witnesses," sources said.

Delhi BJP president Adesh Gupta said Chief Minister Arvind Kejriwal should sack Khan from his Waqf Board chairmanship.