Underworld don Abu Salem, who was brought to New Delhi from Mumbai in connection with an extortion case, was remanded on Monday to four days' police custody by a court to facilitate his interrogation in another similar case.

Allowing the Special Cell's request, Chief Metropolitan Magistrate Seeme Maini granted custodial interogation of Salem to carry out a probe in an eight-year-old extortion case, in which Romesh Sharma is a co-accused.

"The investigation has to go through a proper channel and sustained interrogation is required. I grant four days police custody for Salem till June 1," the magistrate said.

In the case, Salem, in criminal conspiracy with Romesh Sharma, had in November, 1998, demanded Rs 50 lakh from a South Delhi-based businessman Vinay Singh. A case was registered with Hauz Khas Police Station.

Salem, who was an accused in the 1993 Mumbai serial bomb blasts case, was brought to the capital last week in pursuance of the production warrant issued by the Delhi court against him on April 17.

There are three criminal cases registered against him, two related to attempted extortion and one under the MCOCA for organised crimes.

Meanwhile, the court also sent Salem to 14 days' judicial custody in another case of extortion, in which he had allegedly demanded Rs 1 crore from Nagrath, owner of Allied Communications in South Delhi, six years ago.