NEW DELHI, Sept. 3 -- India's service sector saw its strongest growth in 15 years in August, driven by a surge in demand and new business, according to a private survey released on Wednesday.

The HSBC India Services Purchasing Managers' Index (PMI), compiled by S&P Global, climbed to 62.9 in August, up from 60.5 in July and 60.4 in June. This marks the fastest growth since June 2010. The index has now remained above the 50-point threshold, which separates growth from contraction, for over four years, highlighting the sector's sustained momentum.

According to the survey, the rise in international sales was the third-strongest since the series began in 2014. This robust demand led services firms to hire more workers, although outstanding ...