Abu Salem, who was arrested and extradited from Portugal in 2005 for his alleged involvement in the 1993 Mumbai terror blasts, was on Monday brought to Delhi for questioning in two cases of extortion.
Salem was brought from Mumbai by the Golden Temple Express under special security.
"We have formally arrested Salem after the Mumbai TADA court granted his custody to us for his alleged involvement in the two extortion cases. He would be produced in the court on Tuesday," a senior police said.
Delhi Police were seeking Salem's custody since January last year in connection with the two cases registered against him in New Delhi. But the Terrorist and Disruptive Activities (Prevention) Act court had turned down the request, stating that he was required in the 1993 blasts investigation and also in other cases.
Police said Salem is wanted in connection with an extortion case of July 2002. He had allegedly demanded Rs 10 million from Rajat Nagrath, owner of Allied Communications in East of Kailash in south Delhi.
The Special Cell of Delhi Police had earlier arrested three people, Ishtaq, Sadiq and Chandu Prakash, in connection with the case.
Police said they had disclosed that the threats given to the businessman were carried out at the instance of Salem.
Police will also question him for his alleged role in an extortion call to Ashok Gupta, a Greater Kailash I-based businessman, demanding Rs 50 million from him as 'protection money' in April 2002.
Salem was extradited to India on November 11, 2005 - 12 years after he allegedly masterminded the terror blasts in India's financial capital. He was brought to India along with former Bollywood actress Monica Bedi.
Apart from the Mumbai blast case, the 36-year-old mobster is also wanted in 54 cases ranging from murder to extortion.
Salem and Monica were arrested at a Lisbon shopping mall on September 18, 2002 following an Interpol red corner notice issued at CBI's behest.