The notices were served to the duo last night, civic officials said today.
"The purpose for which the site was alloted (for Thackeray's cremation) is over. Therefore, we have asked both Prabhu and Raut to remove the structure immediately or face legal consequences," Municipal Commissioner Sitaram Kunte told PTI.
The 86-year-old Sena chief was cremated on November 18 at Shivaji Park, the same ground where he had addressed his followers during Dassera rallies for over 40 years and the party is keen to have Thackeray's memorial there.
Last week, Sena had equated the edifice where Balasaheb's last rites were conducted at Shivaji Park, to Ayodhya. "The sanctity of the place should be maintained. It is like a temple for us and we won't remove the structure that has come up at the cremation site," Raut had told reporters.
He had also asked the government and court not to intervene in the issue. Senior party leader Manohar Joshi first made the demand for the memorial of Bal Thackeray at the site, soon after he was cremated on November 18. Thackeray died on November 17 at his residence 'Matoshree'.
Earlier, Maharashtra Chief Minister Prithviraj Chavan said that the state government would not do anything in violation of the law with regard to Sena's demand to set up a memorial at the spot as the matter with regard to Shivaji Park, which has been declared as a silence zone, is pending in the High Court.
While government is of the view that it is a recreation ground, the court says it is a play ground in which case no construction will be possible, he had said.