SINGAPORE - Citigroup said Thursday it would defend itself against a lawsuit filed by a Singapore tycoon who alleged he lost one billion dollars (687 million US) on trading deals due to the bank's negligence.

Oei Hong Leong, one of Singapore's wealthiest individuals, is suing Citigroup's private banking arm for allegedly failing to give him an accurate picture of his trading exposure, leading to the losses.

'We fully intend to defend our position vigorously,' a Citigroup spokesman said in a statement to AFP.

The hearing for the lawsuit is scheduled for June 23, a court official said but gave no further details.

The Straits Times reported this week that Oei had paid off his losses from foreign exchange and US Treasury bond deals but was now suing the US banking giant's private banking arm for negligence and misrepresentation.

Oei, who was born in Indonesia, alleged that the bank painted an inaccurate picture of his trading exposure in the financial markets which led him to make decisions that ultimately caused him to lose the money.

But Citigroup said in its statement: 'We have acted professionally in managing Mr Oei's account.'

'We have comprehensive and robust systems and processes in place to handle client orders and transactions and for monitoring and control.'