Indian and US counsel have helped Indian start-up Reliance Petroleum Limited close the subcontinent's largest-ever initial public offering.

Amarchand Mangaldas, Khaitan & Co and Junnarkar & Associates took the primary local roles on the offering by Reliance, which is constructing what will become part of the world's largest refinery complex. US heavyweights Milbank Tweed Hadley & McCloy and Davis Polk & Wardwell landed the two key international roles, advising the underwriters and the issuer respectively.

Closing in May, the IPO has raised Rs270bn (US$600m), which represents 10% of the post-IPO capital of the company - which in turn is 75% owned by Reliance Industries, the largest business group in India, while Chevron has a 5% ownership stake.

London-based partner Tom Siebens led the Milbank team, which included Hong Kong managing partner Anthony Root, Washington DC-based corporate partner Glenn Gerstell, and New York-based tax partner Andrew Walker. In addition to representing the commercial bank lenders to the project, in Mumbai the US firm advised the nine book-running lead managers on the IPO. Led by JM Morgan Stanley and DSP Merrill Lynch, the book-running lead managers turned to Khaitan & Co on local law issues.

Meanwhile, Reliance turned to Junnarkar & Associates for Indian law matters in addition to Davis Polk. Amarchand Mangaldas served as special counsel on the transaction.

"Despite challenges presented by recent changes in Securities and Exchange Board of India guidelines, new developments during the process - such as the Chevron investment - and the sheer size of the domestic offering, we were able to complete this transaction in just three months. And that included the 30 days required for review of the offering document by the SEBI," said Milbank lead partner Siebens.

"Success was a result of the very close coordination among the company's team, the nine lead managers, legal counsel, SEBI and the auditors. The spread of our team allowed the round-the-clock coverage necessary at times," he added.

Reliance Petroleum Limited is a start-up company formed to set up a greenfield petroleum refinery and polypropylene plant in a Special Economic Zone in Jamnagar in the state of Gujarat in western India, near the Pakistan border. In addition to the IPO, funding for the refinery and plant has been provided by Reliance Industries and institutional shareholders, with additional financing expected from banks, export credit agencies and others.