"Talk to AK", the maiden interactive session of Delhi Chief Minister Arvind Kejriwal, was held on July 17 last year. The programme, in which Mr Kejriwal discussed an array of hard issues including the relations between the Centre and the Delhi government, was live streamed on the website www.talktoak.com.
"The central government's motive is to finish the opposition," the Aam Aadmi Party said, accusing the centre of behaving in a "dictatorial" manner.
Aam Aadmi Party leaders said the programme generated wide interest. The BJP and the Congress called it a marketing gimmick at the cost of the exchequer. The questions and answers, the two parties had alleged, were "scripted".
The CBI started the preliminary inquiry after a complaint was filed by the Vigilance Department. It alleged that a consultant of a well-known public relations company, Perfect Relations, was hired by the Delhi government to promote the "Talk to AK" campaign and a proposal of Rs 1.5 crore was prepared for this purpose.
The CBI's preliminary inquiry will look into the alleged role of Mr Sisodia and others.
After the announcement of the CBI inquiry, Mr Kejriwal alleged that the Centre was "gunning" for the AAP government. So far, 19 legislators of the party have been arrested in various cases.