Maharashtra Navnirman Sena leader Bala Nandgaonkar on Wednesday met Maharashtra Home Minister Dilip Walse-Patil over a letter threatening Raj Thackeray, and demanded action.
Speaking to reporters later, he said there would be repercussions across the state if the MNS chief was harmed.
Mumbai Police, meanwhile, registered a case in connection with the anonymous letter.
His office received the letter, Nandgaonkar said, adding that it was written in Hindi with a smattering of Urdu words and referred to Thackeray's warning that the Hanuman Chalisa would be played in front of mosques if loudspeakers were continued to be used to broadcast 'azaan' (the Muslim call to prayer).
"The home minister said he will talk to the police commissioner. Now they will take whatever action that is necessary. But if even the slightest harm comes to Raj Thackeray, Maharashtra will burn. The state government has to take note of this," Nandgaonkar added.
He had met Mumbai police commissioner Sanjay Pandey over the letter on Tuesday, he said.
Nandgaonkar also said that he had been asking for security for the MNS chief and his family, but the state government was not paying heed. The Union government should look into this, he said.
Meanwhile, a non-cognisable offence was registered against unidentified persons under section 507 (criminal intimidation by anonymous communication) of the Indian Penal Code at Kalachowki police station in connection with the letter, said an official, adding that police are conducting further probe.
Raj Thackeray had given an ultimatum last month that loudspeakers be removed from mosques in the state by May 4.
