The announcement by the Hong Kong Monetary Authority, the city's de facto central bank, comes a day after UBS agreed to pay £940 million in fines for trying to manipulate the Libor interest rate affecting borrowers globally.
The HKMA said on its website that it has launched a probe to determine whether there was any wrongdoing by UBS when it submitted information used to set the Hong Kong Interbank Offered Rate. It will also try to find out if the misconduct had any "material impact" on setting the rate, known as Hibor.
The authority said it was tipped off by other regulatory authorities about the possible misconduct involving the rate and other key ones in the region.
UBS said it would "work closely with various regulatory authorities to resolve issues relating to the setting of certain global benchmark interest rates", but would not comment further because it is in "active discussions with these authorities."
On Wednesday UBS agreed to pay £940 million in fines in a settlement with US, British and Swiss regulators.
The bank said some of its employees tried to rig the Libor ( London Interbank Offered Rate), in several currencies.
Libor is set daily using information that banks provide and is used to price trillions in contracts around the world, including mortgages and credit cards.
Hibor is used mainly by Asian lenders and borrowers.