The administration has identified 53 unauthorised structures in the CRZ in suburban Versova, he said.
Social activist Abdul Choudhary had earlier written to the Maharashtra Coastal Zone Management Authority (MCZMA), asking it to initiate steps to demolish the structures. The letter was forwarded to the district administration.
"We have received the complainant's letter but even before that, we had issued notices to MHADA (housing board) and BMC seeking details from them.
"Recently, we demanded that MHADA initiate action against structures that violate CRZ norms and had given them 15 days time," said Deependra Singh Kushwah, Mumbai suburban collector.