New Delhi, Aug 27 :  The walls of several metro stations across Delhi were found defaced with pro-Khalistan and anti-PM graffiti ahead of the G20 Summit on September 8-10, police said on Sunday. The police received information that slogans were written at more than seven metro stations. A senior police officer stated that upon receiving the information, they promptly dispatched teams to each metro station. "Derogatory slogans challenging the sovereignty of India were discovered at the following metro stations: Shivaji Park, Madipur, Paschim Vihar, Udyog Nagar, and Maharaja Surajmal Stadium; as well as Punjabi Bagh and Nangloi Metro Stations. The accused also defaced the Government Sarvodaya Bal Vidyalaya Nangloi with slogans. Khalistani supporters might be behind this act ahead of the G-20 Summit," police source told IANS. Slogans such as 'Delhi Banega Khalistan' and 'Khalistan Referendum Zindabad' were found sprayed on the walls. The accused also mentioned the name of Sikhs for Justice (SFJ) along with the slogans. The police have formed multiple teams to investigate the matter. They have affirmed that those involved in these incidents will not be spared. The police were examining the CCTV footage from nearby areas and metro stations to identify the culprits responsible for writing these slogans. /IANS