HONG KONG, Aug 25 (Reuters) - The Hong Kong Monetary Authority sold HK$643 million ($83 million) into the market in New York trading hours after the local currency hit the strong end of its trading band, according to data released by the HKMA on Tuesday morning.

The aggregate balance - the key gauge of cash in the banking system - will increase to HK$188.383 billion ($24.31 billion) on August 26, said HKMA.

The Hong Kong dollar is pegged in a narrow range of 7.75-7.85 to the U.S. dollar. The HKMA last conducted sales three weeks ago to keep it within this range. ($1 = 7.7500 Hong Kong dollars) (Reporting by Donny Kwok; Editing by Kim Coghill)