SEOUL, Jan 2 (Reuters) - State Street Bank & Trust Company of Hong Kong made the first dollar/won trade after South Korean authorities opened up the interbank market to foreign financial institutions under a pilot programme from Tuesday, sources familiar with the deal said.

The trade was conducted with Hana Bank, according to the sources who declined to be identified as they are not authorised to speak to media.

South Korea in October began accepting applications from foreign financial institutions to review permits to participate in the onshore dollar-won interbank market in a bid to encourage more foreign participation.

"This transaction is the first dollar-won transaction concluded in the Seoul foreign exchange market between a foreign financial institution (RFI) located overseas," a Hana Bank official said.

The government also plans to extend onshore trading hours until 2 a.m. KST (1700 GMT), or the closing of London business hours.

Up until the end of 2023, the Korean won could only be directly traded with the dollar through local banks, for just six-and-a-half hours a day between 9 a.m. (0000 GMT) and 3:30 p.m. (Reporting by Yena Park, Cynthia Kim; Editing by Jacqueline Wong)