Two aides of Iqbal Kaskar, the brother of fugitive don Dawood Ibrahim, were today arrested in connection with an extortion case, a senior police official said.

Kaskar and his associates had allegedly been threatening a prominent builder in Thane, in Dawood’s name since 2013 and extorted Rs 30 lakh and four flats from him, police said.

Mumtaz Sheikh and Israr Ali Jamil Sayyad, who were earlier detained, were formally placed under arrest, Thane’s Commissioner of Police Param Bir Singh said.

Besides, Iqbal Parkar, a close relative of Haseena Parkar, Dawood’s sister, and drug dealer Mohammad Yasin Khwaja Hussain were also detained in connection with the case, the officer said.

Kaskar was last night taken into custody from his sister Haseena’s house in Nagpada area of Central Mumbai, by a team led by encounter specialist and the anti-extortion cell’s senior police inspector Pradeep Sharma.

He was questioned till late last night by the crime branch officials and then formally arrested, Singh said.

The police are also investigating if Dawood Ibrahim had any role in the matter and if it is found, he will also be made an accused in the case, the commissioner said at a press conference here.

Kaskar and his associates allegedly demanded Rs 30 lakh and four flats from the builder in Dawood’s name. He had also sent his aide to the builder’s office and at the construction site to extort money, Singh said.

The builder later gave four flats worth Rs 5 crore and Rs 30 lakh in cash to Kaskar but then also he was being threatened by the accused, the police said.

Out of the four flats, three were sold and one was registered in the name of Sayyad, who was staying in it for the last few years, the senior police officer said.

A few days ago, an extortion case was registered on the basis of the complaint by the builder at Thane’s Kasarwadavali police station under IPC section 384 (extortion), 386 (extortion by putting a person in fear of death or grievous hurt) and 387 (putting person in fear of death or of grievous hurt, in order to commit extortion).

Later, the case was handed over to the Thane Police’s anti-extortion cell.

During investigation, the police initially nabbed Sheikh and Sayyad from Thane. Later, Kaskar’s name also cropped up in the case, police said.

The names of some builders and politicians, including corporators, have allegedly also come up during the investigation in the case, Singh said.

“We are investigating whether they were helping Kaskar in the extortion racket. If needed, we will also take help of the Enforcement Directorate and verify whether the Maharashtra Control of Organised Crime Act (MCOCA) can be applied in this case,” the commissioner said.

Kaskar, who was deported from the United Arab Emirates 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, the police said.