An Indonesian couple who lost money from a failed foreign exchange trade during the 2008 financial turmoil are suing UK-listed Standard in Singapore and claiming it breached its duties, according to the Straits Times (of Singapore).

Soesanto Prajogo and his wife Lioe Lip Joeng are demanding damages of $2.441 million over one bank action and A$40,000 ($37,900) for another alleged breach.

The couple opened accounts with American Express Bank in 2001 and held deposits in Singapore. When StanChart bought American Express Bank in 2008, they became its private banking clients in July of that year - and remain so today, the report said.

In the early morning of Oct7, 2008, StanChart closed out the clients' New Zealand dollar-US dollar positions without receiving instructions or authority from them, according to the writ of summons filed in August in the High Court. The couple claim they had more than enough collateral in the bank to avoid a margin call, the report continued.

StanChart has "failed, refused or neglected" to provide the couple with a reasonable or adequate explanation as to why the position was closed unilaterally, stated the writ of summons, it said.

The couple are also unhappy with an incident in mid-2009, when they say StanChart failed to execute a A$10 million forex option despite an instruction from Mr Prajogo, it said. In both cases, StanChart acted "wrongfully and in breach of its duties", they said.

StanChart has reportedly disputed the couple's version of events in its defence filed on Wednesday this week.

The bank said the account had dropped into a margin shortfall on the night of Oct 6, 2008, and early morning of 7 October. This account had NZ dollar-US dollar and Aussie-US dollar positions open and the greenback gained sharply against both.

StanChart reportedly said the night-desk trader during those hours tried to call Mr Prajogo on his mobile and house phone numbers but could not contact him. It then closed out the couple's NZ dollar-US dollar positions.