The Enforcement Directorate (ED) on Wednesday put Maharashtra minister and Nationalist Congress Party (NCP) leader Nawab Malik under arrest in connection with the money laundering case against underworld don Dawood Ibrahim and his aides.

The probe agency has been questioning Nawab Malik since 8 am today. Following the arrest, Nawab Malik was taken to hospital for a routine medical check-up.

According to sources, Nawab Malik was issued summons to appear before the ED in a case registered against underworld don and terror financer Dawood Ibrahim, his brother Anees, Iqbal, aide Chota Shakeel and others.

The agency is looking into a Kurla property deal of Malik, among others. The property was allegedly bought by Malik from an aide of Dawood Ibrahim at a price lower than its prevailing market rate, said sources.

While Malik was being questioned, NCP workers protested near the party's headquarters, located close to the ED office in south Mumbai, and shouted slogans slamming the BJP-led central government and the probe agency.

Reacting to the allegations against Malik, NCP chief Sharad Pawar said invoking Dawood was a convenient way to sully someone's reputation. "I don't know about the case against him but Dawood's name has always been invoked to try to defame rivals," he said. Pawar claimed that he was also accused of having ties with the underworld when he was the state's Chief Minister.

This is the second arrest of a top minister in the alliance government of the NCP, Shiv Sena and Congress.