A bench of Acting Chief Justice Gita Mittal and Justice C Hari Shankar directed the police to "conduct a prompt investigation" and "bring the culprits to book".
The court issued the directions on an application moved by H D Nijhawan, the General Secretary of the NGO Paardarshita Public Welfare Foundation, claiming he was brutally assaulted by some persons here last evening.
The applicant claimed that he was saved after passersby raised alarm which led the assailants to flee.
The NGO has filed several PILs in the high court against unauthorised construction in various parts of the city and alleging that such illegal buildings come up with the active connivance of the officials of the municipal corporations and Delhi Development Authority (DDA).
In some of these matters, the high court has also ordered a CBI probe to ascertain the role of the officials responsible for permitting unauthorised constructions to come up.