Prabhakar Sail, an independent witness of the Narcotics Control Bureau (NCB) in the drugs-on-cruise case involving Aryan Khan, died of a heart attack at his residence in suburban Chembur, police said on Saturday.

"Prabhakar Sail, 37, died of a heart attack at his house in Mahul on Friday evening," a police official said.

The death will be probed separately, reports NDTV quoting Maharashtra Home Minister Dilip Walse Patil.

Sail was rushed to the civic-run Rajawadi Hospital in Ghatkopar, where he was declared brought dead, he said.

Sail's lawyer Tushar Khandare confirmed that Sail died after he suffered a heart attack and that his family members do not suspect any foul play.

Sail, who claimed to be the bodyguard of NCB witness K P Gosavi, had alleged in an affidavit that he had heard Gosavi discuss a Rs 25 crore pay-off deal after Aryan Khan was arrested during a raid on a cruise ship off the Mumbai coast on October 3 last year.

The NCB had told the court that Sail had turned hostile and his affidavit was still pending before the court.

Aryan Khan was named an accused in the case along with 19 others by the NCB. The accused persons were booked under relevant sections of the Narcotics Drugs and Psychotropic Substances (NDPS) Act for alleged possession, consumption, sale/purchase of banned drugs, conspiracy and abetment, among others.

Of the 20 arrested accused in the case, only two are currently in judicial custody and the rest are out on bail.