A lawyer seconded to the Libyan Investment Authority, which is suing Goldman Sachs over $1 billion of trades that ended up worthless, was "shocked" by the bank's "inappropriate" relationship with the fund, according to court filings.

In a suit filed at London's High Court, the Libyan Investment Authority (LIA) claims the Wall Street investment bank exploited a position of trust by encouraging the sovereign wealth fund to invest more than $1 billion in a series of equity derivatives trades that expired as worthless in 2011.

The fund, which became a Goldman client in 2007, alleges the trades "whilst extremely profitable for GSI (Goldman Sachs International), were inherently unsuitable for a sovereign wealth fund like the LIA", court documents show.

Goldman on Monday reiterated an earlier statement saying it believes this case is entirely without merit and that it intends to contest it vigorously.

In a witness statement released as the two parties met in court for the first time on Monday, Catherine McDougall, who was seconded to the LIA while working at London law firm Allen & Overy, described her discussions with the fund's equity team about the disputed trades.

"None of the equity team understood in any depth what the disputed trades involved," she said in the statement. "I asked them where the due diligence was and they responded "due what?""

"BLURRED" LINES

McDougall, who said she left Allen & Overy in 2008 amid the fallout related to the trades, said LIA employees were wholly reliant on Goldman's advice and seemed not to question it.

She said in the statement to the court that the equity team considered one Goldman employee to be their very close friend, trusting him 100 percent.

"They told me about their lavish trip to Morocco and that there was heavy drinking and girls involved," she said.

She said she thought the level of closeness "seemed inappropriate and that the line between friendship and arm's length commercial dealings had clearly been blurred."

In documents Goldman submitted to the court, the bank called the LIA's allegations "remarkable" and "utterly unconvincing" and argued the LIA was well-equipped to understand the trades.

"(The LIA) had a board of directors, a board of secretaries, and an advisory committee, and its executives included highly experienced banking professionals," it said.

"The claim is a paradigm of buyers' remorse."

Goldman said the trades turned out badly because of the collapse of financial markets in 2008 and defended the conduct of its employees who worked with the fund.

"Trusting one another is just a description of ordinary commercial life. A relationship of banker and customer does not normally give rise to any presumption of undue influence."

The LIA has proposed that a trial lasting around 25 days take place at some point between January and March in 2016. – Reuters