The ministry of environment and forests (MoEF) on Tuesday asked Adarsh Cooperative Housing Society for clarifications on the floor space index (FSI) of a plot meant for a bus depot that was transferred to the society. Adarsh has till January 10 to reply.
FSI specifies how high a structure can be built.
"By the end of next week, we will decide what action to take… All options, including demolition, are open," Union environment minister Jairam Ramesh said.
Adarsh's lawyer, Satish Maneshinde, said they would give the clarifications and refused to comment further.
Adarsh members had a hearing with the MoEF on Tuesday. This followed a show cause notice on November 12 pertaining to the allegedly illegal construction in the Coastal Regulation Zone.
The Urban Development Department said that in 2005 it allowed Adarsh to use the FSI of the 2,669 sq mt plot because it was 'underutilised'.
While FSI should have been used to build staircases, elevators and a lobby, Adarsh members instead raised the building's height by 30 mt, the report said.