Singapore  - A Singapore businessman sued Citigroup Inc's private banking arm for negligence and misrepresentation after he lost 1 billion Singapore dollars (683 million US dollars) on foreign exchange and bond trades last year, media reports said Tuesday.

Oei Hong Leong, 60, claimed the bank, with which he had a 30-year business relationship, repeatedly gave him an inaccurate picture of his trading exposure, causing him to take on more positions than he would have taken otherwise, the Straits Times newspaper reported.

Oei, ranked Singapore's 27th richest man by Forbes magazine last year with a net worth of 210 million US dollars, said he felt compelled to close his positions at an extremely volatile time last October after discovering the full extent of his exposure, thus suffering huge losses.

Citigroup denied the allegations.

"We believe that the claim is without merit and we fully intend to defend our position vigorously," the report quoted a Citi spokesman as saying. (dpa)