Goldman Sachs has rejected allegations by an Indonesian businessman who is seeking $1.1 billion in damages from the U.S. bank for making what he called "unlawful" trades in the shares of a property firm.

The U.S. bank said the legal dispute may affect foreign investor sentiment towards Southeast Asia's biggest economy.

Indonesia's government has recently raised investor concerns by cutting business ties with JPMorgan over a negative research report and partially reversing a mining policy.

Benny Tjokrosaputro, president director of Indonesian property developer PT Hanson International Tbk, filed a lawsuit in a Jakarta court on Sept. 8 against Goldman's unit, Goldman Sachs International.

Tjokrosaputro was the owner of the 425 million Hanson shares that Goldman traded, according to a statement on his lawyer's website. "(The) transaction was conducted unlawfully and/or without the consent of our client." (http://bit.ly/2k8op50)

In an emailed statement on Friday, Goldman said Goldman Sachs International bought the shares from New York hedge fund Platinum Partners in a series of "valid" transactions on the Indonesia Stock Exchange between February 2015 and March 2016.

Top executives of Platinum Partners were arrested in December and charged with running a $1 billion fraud.

Tjokrosaputro is seeking 15 trillion rupiah ($1.1 billion) in compensation from Goldman Sachs International and wants its assets frozen in Indonesia and overseas.

Citibank, a custodian bank for Goldman Sachs International, was named as a co-defendant in his lawsuit.

Goldman said in response that Goldman Sachs International was the legal owner of the Hanson shares. "Any business dealings or deal made between Mr. Tjokrosaputro and Platinum Partners before this have no bearing or obligation on Goldman Sachs," it said.

The bank would take "all necessary action to protect itself and recover damages from Mr. Tjokrosaputro," it said, without elaborating.

It also said that Tjokrosaputro's "unfounded actions" risked undermining Indonesia's effort to attract international investment and threatened the integrity of Indonesia's stock market.

"All investors in Indonesia should be free to trade with confidence, without fear that legitimately executed trades will later be subject to spurious legal action by unconnected third parties," Goldman said.

Tjokrosaputro and his lawyer did not respond to requests for comment on Friday. Citibank was not immediately available for comment.