OSLO (Reuters) - A shipping magnate who founded several Bermuda-based companies said a US government lawsuit against his trading companies might be a bid to take revenge for oil major BP’s oil spill last year by targeting former BP traders who now work for him.Billionaire John Fredriksen told Reuters his oil trading firms being sued by the US government for suspected oil price manipulation, had done nothing illegal and their practices were no different from those of other major traders.The interests of Mr Fredriksen, a Norwegian-born Cypriot, include the world’s largest oil tanker operator Frontline, dry bulk shipper Golden Ocean Group and offshore driller Seadrill, all of which are based in Bermuda.“Maybe the problem is that these guys (the traders) worked for BP and they made a lot of money for BP before,” Fredriksen, looking relaxed but perplexed by the media attention directed at him in the past two days, told Reuters.“Maybe they (US authorities) are trying to get some revenge,” said Fredriksen, referring to BP’s deepwater accident in the Gulf of Mexico, which led to the worst oil spill in US history.US regulators on Tuesday launched one of the biggest ever crackdowns on oil price manipulation, suing two well-known traders and two trading firms owned by Fredriksen for allegedly making $50 million by squeezing markets.The Commodity Futures Trading Commission said traders James Dyer of Oklahoma’s Parnon Energy and Nick Wildgoose of Europe-based Arcadia Energy, amassed large physical positions at a key US trading hub to create the impression of tight supplies that would boost oil prices.Later they dumped those barrels back onto the market, causing prices to crash and racking up profits from short positions they had accrued in futures markets, the suit said.Fredriksen said that what the traders had done was quite normal practice among oil traders.“It is quite normal. It is the same for Glencore, and Vitol, and these other guys... It is nothing,” he said adding he was “shocked” when he heard about the CFTC investigation.“I did not know a thing about it I have about 50 companies, how can I follow everything?,” said Fredriksen, a self-made billionaire who started out as a messenger boy.“Oil traders, they are supposed to buy and sell,” Fredriksen said. “I don’t think it is illegal but I am not an expert on oil trading, so I don’t see the problem.”