Japan's services sector gained momentum in April, with the au Jibun Bank Flash Services Business Activity Index rising to 52.2, up from 50.0 in March, according to S&P Global's preliminary report released Wednesday.

The Flash Composite Output Index, which tracks overall private sector activity, also rose to 51.1 from 48.9 in March.

"Japan's private sector returned to growth in April, with firms signalling an increase in business activity for the fifth time in six months," Annabel Fiddes, Economics Associate Director at S&P Global Market Intelligence, stated in the report.