Oil rigs in Nigeria, ships, a business jet and a plush flat in London were among the assets, worth over Rs 9,700 crore, attached by the Enforcement Directorate (ED) on Wednesday as part of its bank fraud and money laundering probe against Gujarat-based pharmaceutical firm Sterling Biotech.

The Enforcement Directorate said it has issued a provisional order under the Prevention of Money Laundering Act (PMLA) for attachment of these properties.

This is one of the biggest attachment of assets order issued by the agency and in this, most of the properties attached are based abroad, a senior official said, adding that the total value is Rs 9,778 crore.

Four oil rigs and an oil field named OML143 in Nigeria, four Panama registered ships --'Tuljabhawani', 'Varinda', 'Bhavya' and 'Brahmanietc', a Gulfstream jet registered in the US and held in the name of SAIB LLC, and a residential flat in London have been attached, the federal probe agency said in a statement.

The holding company of the ships is Atlantic Blue Water Services, it said. The alleged Rs 8,100 crore bank loan fraud is being alleged to have been perpetrated by the Vadodara-based pharma firm and its main promoters Nitin Sandesara, Chetan Sandesara and Deepti Sandesara, all of whom are absconding.

The Sandesaras are also under probe for their alleged nexus with some high-profile politicians by the ED as also by the CBI and the Income Tax Department under criminal sections that deal with corruption and tax evasion respectively. The ED, in the past, has attached assets worth Rs 4,730 crore in this case.

"The main promoters (of the Sterling group) have not only siphoned off loan funds to finance their Nigerian oil business but also for their personal purposes," the agency said. It said loan funds were "diverted for non-mandated purposes, layered and laundered through a web of multiple domestic as well as offshore entities."

"Investigations revealed that the group was engaged in round-tripping of standby letters of credit (SBLCs) funds to the tune of Rs 4,500 crore by violating conditions laid by the RBI while sanctioning the loan," the ED said.

It is alleged that the company took loans of over Rs 5,383 crore from a consortium led by Andhra Bank, which had turned into non-performing assets.

The total volume of the alleged loan defraud is pegged at Rs 8,100 crore.

"The said SBLCs were later on devolved on the guarantor banks causing wrongful loss to these public sector banks and to the public at large. Their strategy included incorporation of multiple shell companies, conducting circular transactions to artificially inflate turnover of flagship companies, claiming higher depreciations on non-existing machinery to avoid tax liabilities, artificial share trading with the shell companies, layering and laundering of proceeds of crime within India and abroad through the web of multiple shell companies," the ED alleged.

It charged that the "promoters (Sandesaras) incorporated 249 domestic and 96 offshore shell companies" to execute the alleged bank loan scam. The ED registered a criminal case in the alleged bank loan fraud case based on a Central Bureau of Investigation FIR and charge sheet.

The promoters of the firm, also alleged to be the main conspirators of the bank fraud apart from their employees and bank executives, are absconding and have been reported to be based in Nigeria from where India is trying to extradite them.