India, June 5 -- Former Public Works Department (PWD) minister Satyendar Jain is the primary focus of the investigation being carried out by Delhi government's Anti-Corruption Branch (ACB) into the alleged irregularities in the construction of classrooms, while formed deputy chief minister Manish Sisodia is being probed for giving post-facto approval to the project, officials aware of the matter said on Wednesday.

Jain has been summoned to appear before the bureau on June 6, and Sisodia on June 9. Both Aam Aadmi Party (AAP) leaders are to be questioned at the ACB's office in central Delhi.

Senior ACB officials said the investigation was launched based on statements by contractors and architects, many of whom have pointed to Jain's direc...