Those taken into custody under the provisions of the Prevention of Money Laundering Act (PMLA) have been identified as Antu Tirkey, Priya Ranjan Sahay, Bipin Singh and Irshad, they said.

The ED had on Tuesday conducted searches at the premises of Tirkey and some others here.

With these arrests, the total number of people taken into custody in this case has risen to eight.

Soren, 48, was arrested by the ED in January shortly after he resigned as the chief minister. He is currently lodged in Birsa Munda jail at Hotwar here under judicial custody. Prime accused and former revenue department sub-inspector Bhanu Pratap Prasad, Mohammed Saddam Hussian and Afshar Ali have also been arrested.

The probe against Soren pertains to an 8.86-acre plot of land in Ranchi that the ED has alleged was illegally acquired by him.

The agency had filed a charge sheet against Soren, Prasad and Soren's alleged "frontmen" -- Raj Kumar Pahan and Hilariyas Kachhap -- and alleged associate of the former CM Binod Singh before a special PMLA court here on March 30.

The ED has also attached the Ranchi land and requested the court for confiscation of the plot.

The money laundering investigation stems from multiple FIRs registered by Jharkhand Police in land "scam" cases against several people, including state government officials.

The prime accused in the case is Prasad, who was the custodian of government records. He is alleged to have "misused" his official position by providing assistance to several people, including Soren, in their activities linked to illegal occupation, acquisition and possession of proceeds of crime in the form of landed properties, the ED had said in a statement.

"A racket of land mafia is active in Jharkhand which used to forge the land records in Ranchi," it had claimed.