Sixty-six companies based in Tokyo paid their employees 2.27 billion yen in unpaid overtime between October and March after the Tokyo Labor Bureau instructed them to stop withholding the pay, officials said Wednesday.

The bureau officials said the results for the six-month period were a sharp increase from the roughly 1.5 billion yen paid out by 67 companies in the 18 months between January 2001 and last June -- the last time the bureau compiled such figures.

The bureau's order involved 21,510 workers at 672 offices of the 66 firms, according to the report.

The bureau -- a local branch of the Health, Labor and Welfare Ministry -- compiled the report on firms that forked out 1 million yen or more in unpaid overtime based on the findings of regular inspections, as well as checks conducted as a result of information from employees and other sources, according to the officials.

Under the Labor Standards Law, companies are required to pay at least 25 percent more of a person's ordinary hourly wage for overtime hours or hours put in at work on holidays.

A bureau official attributed the rise to the recession, which has forced firms to handle the same workload with fewer employees as they pare staff numbers to cut costs.

Many workers have also become hesitant to complain to their employers about unpaid overtime out of fear they will be fired, the official added.

The bureau is encouraging employees to report unpaid overtime and will step up its inspections to combat the problem, the official said.