Kaskar, along with his aides Israr Jamil Sayyed and Mumtaz Ejaj Shaikh, was produced before magistrate RT Ingle today.
Thane police's crime branch had arrested Kaskar and others on September 19 for allegedly threatening a Mumbai builder using Dawood's name.
Prosecutor Rashmi Kshirsagar told the court that police were yet to arrest four shooters from Bihar whom the gang had hired to intimidate the builder. Advocate S Keswani, the accused's lawyer, said the investigation details revealed by police had no bearing on the case, and the media was publishing them.
The magistrate agreed to extend police custody of the three accused after hearing both sides.
The police alleged that Kaskar and his associates had been threatening the builder in Thane, in Dawood's name since 2013 and extorted Rs 30 lakh and four flats from him.
Kaskar, who was deported from the United Arab Emirates (UAE) in 2003, is said to be operating Dawood's real estate business in the city, according to the police.
He was wanted in a murder case and the Sara Sahara illegal construction case. He was, however, acquitted in both the cases in 2007.