TOKYO, June 25 (Reuters) - The price Japanese companies charge each other for services rose 2.5% in May from a year earlier, data showed on Tuesday, a sign prospects of steady wage increases are prompting more companies to pass on higher labour costs.

The year-on-year increase, however, slowed from the previous month's 2.7% gain, Bank of Japan (BOJ) data showed.

An index measuring the price companies charge each other for services with high labour costs rose 2.5% in May from a year earlier, unchanged from April, the data showed. (Reporting by Leika Kihara; Editing by Muralikumar Anantharaman)