The Hong Kong Monetary Authority has sold $603 million worth of Hong Kong dollars in the foreign exchange market in an effort to curb the currency's rise, a report said.

The move on Saturday came as the US dollar hit HK$7.75, the lower limit of the trading band in which the greenback is allowed to trade against the local currency, Dow Jones Newswires reported.

The Hong Kong dollar is typically allowed to trade in a narrow range between HK$7.75 and HK$7.85.

The HKMA said demand for the local unit was robust due to a weakness in the US dollar and stabilisation of European markets, which triggered capital inflows to Asian currencies and stocks.