The average monthly wage hike rate among big companies in Japan has topped 5 percent for the first time since 1991, when the Asian nation experienced an asset-inflated bubble economy, the country's largest business lobby said Monday.

The rate, including regular salary increases and base pay rises, averaged 5.58 percent, the survey by the Japan Business Federation showed, as private firms try to safeguard the lives of their employees from sharp price hikes at home.

The average increase in monthly wages by companies responding to the organization, known as Keidanren, was 19,210 yen ($135), the highest figure since 1976, the year the current method of data collection was introduced.

The figures, released as the management side agreed to the major wage hike to ensure manpower and talent, were higher than last year's average wage increase of 3.99 percent and 13,362 yen.

With respect to workers in the public service system, the National Personnel Authority is planning to advise a monthly pay raise of over 2 percent to parliament and the Cabinet as early as Thursday, sources familiar with the matter said.

If realized, it would be the first wage hike exceeding 2 percent in 32 years, the sources said Monday. The central government aims to secure competent human resources by improving benefits and working conditions, especially for young people.

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