HONG KONG, July 2 (Reuters) - Hong Kong's May retail sales fell 11.5% from a year earlier reflecting both lower sales volumes and the strength of the Hong Kong dollar, government data showed on Tuesday.

Sales fell to HK$30.5 billion ($3.90 billion) in a third consecutive month of decline after a 14.7% drop in April and a 7% decline in March.

In volume terms, retail sales fell 12.9% year-on-year in May, compared with a 16.5% drop in April and a 8.7% fall in March. ($1 = 7.8122 Hong Kong dollars) (Reporting by Donny Kwok; Editing by xxx)