TOKYO (Reuters) - Japan's inflation-adjusted real wages rose in June for the first time in 27 months and nominal pay gained at the strongest pace in 27 years, led by higher bonuses as more firms increase wages.

The Bank of Japan last week raised interest rates to levels unseen in 15 years and unveiled a detailed plan to slow its massive bond buying. Broadening wage hikes and rising services prices were behind such moves.

Real wages grew 1.1% in June, rising for the first time in 27 months, after a revised 1.3% slip in May, data from the labour ministry showed.

Nominal wages, the average total cash earnings per worker, grew 4.5%, the fastest pace of growth since January 1997, to 498,884 yen ($3,480), compared with a revised 2.0% rise in May.

Special payments rose 7.6% in June, after a revised 0.1% growth in the previous month, thanks to firms increasing wages amid a labour shortage.

Base pay, or regular pay, climbed 2.3% year-on-year in June, marking the fastest pace of gain since October 1994.

Japanese firms agreed to raise monthly pay by 5.10% on average this year, the biggest gain in 33 years.

"We need to monitor whether real wages will continue to rise," an official at the ministry said.

General employees' regular pay increased 2.7% for the month, rising at a record pace.

The consumer price index officials use to calculate real wages, which includes fresh food prices but excludes owners' equivalent rent, rose 3.3% in June, the same rate of gain made in May.

Overtime pay, a barometer of corporate strength, grew 1.3% in the year to June, extending a revised 0.9% rise in May, the data showed.

($1 = 143.3800 yen)