CITIGROUP on Friday rejected a writ by a Singapore private banking client who claimed he lost over S$1 billion because the bank provided inaccurate information and failed to execute some of his trades.

Citi said in a court filing seen by Reuters that businessman Oei Hong Leong "demonstrated a considerable appetite for risk and an understanding of the risk and exposure associated with the various derivative investment structures entered into".

His open positions with Citi had stood as high as US$6.89 billion in February 2008, the bank said.

Many private banking clients lost money in the aftermath of the Lehman Brothers collapse last September that led to turmoil in financial markets.

Citi denied providing Oei with inaccurate and misleading margin numbers, and alleged Oei's claims of a "meltdown" in its tracking and control systems were "contrived afterthoughts".

'We intend to vigorously defend the action. We have today filed our defence,' Citi's private bank said in a statement.

As for Citi's alleged failure to execute US$600 million worth of buy orders for US Treasury bonds placed by Oei, the bank claimed that was because Oei had consistently set his limit prices below the indicative market prices.

Oei's lawyer, Quek Mong Hua, said Citi's denial "was not unexpected", and his team was studying Citi's defence.

Oei, one of Singapore's richest men, last month sued Citi, with which he has a 30-year relationship, for negligence and misrepresentation.

He alleged the bank repeatedly gave him an inaccurate picture of his trading exposure, which led him to take on more positions than he would have taken otherwise.