The ECIR, which is equivalent to an FIR, has been registered under the harsh Prevention of Money Laundering Act (PMLA), 2002.
"We had been keeping a watch on Singh for quite some time on suspicion of money laundering. He facilitated his services for this to various politicians and shady elements as well. He has been accused in a number of cases in Bihar," ED sources said.
Singh is the owner of Patliputra Builders Limited, a construction company, which has executed several residential and commercial complexes in and around the city.
It in fact has a plethora of ongoing building projects at posh locations here, as well as in the National Capital Region, Delhi, ED officials said.
Singh also owns a regional television news channel, they said, adding that he has an Audi car worth Rs 1 crore and owns the luxurious Hotel Patliputra Exotica at Exhibition Road here and a shopping mall located close to it.
He has also invested in a private school at Ara in Bhojpur district of Bihar, they said.
"If we take the declared value of Singh's property, it would be over Rs 30 crore, but its market value will be several times more. Real estate is where maximum money laundering is happening," an ED official said.
Singh, who hails from a very humble background, is closed to a ruling party muscle-man MLA. And an I-T department raid in 2011 yielded unaccounted wealth of several crores of rupees, ED sources said.
Incidentally, the builder had also been jailed a couple of times on different charges, they said.
In an another instance, the ED registered another ECIR against Public Health Engineering Department (PHED) Executive Engineer Sanjay Singh for involvement in money laundering.