The United Kingdom's richest Indian faces an uneasy Diwali weekend following a looming challenge to his two-year-old purchase of a steel plant in Romania, which helped to position his LN Mittal Group as the second largest steel producer in the world.

It was British Prime Minister Tony Blair's friendly letter to his Romanian counterpart, Adrian Nastase, that helped Mittal cement the Ispat Sidex Steel Plant deal.

Now the steel magnate, whose personal fortune is estimated at £2 billion, faces the prospect of legal action from the Romanian family, which owned the land on which the steel plant was built by the former communist regime.

A property restitution programme in Romania allows rightful owners or their descendants to reclaim land that was seized in the past by the communist regime.

"There have been cases where two international banks were ejected on the demands of the true owners," says Romanian legal expert Madelina Dumitrescu. "But it is very much a matter of politics as well."

A spokesman for Mittal's company said, "We purchased Sidex from the Romanian government and no one would be overjoyed to learn that someone is trying to claim land that someone else had purchased in good faith."