TOKYO, June 9 (Reuters) - The Japanese government on Friday called for households and industries around Tokyo to save electricity in July and August to ensure a stable power supply during the peak summer season, though it did not set any numerical targets.

The country's power market is predicted to be less tight this summer in most of the regions than last summer when the government asked for energy conservation across the nation, according to the industry ministry's forecast in May.

But the ministry has decided to ask for the power saving "within a reasonable range" during the two months in the areas, where power is supplied by the Tokyo Electric Power Company Holdings (9501.T), as the reserve ratio is estimated to be below 5%, close to the minimum 3% that ensures stable supply.

The expected reserve ratio, in the event of a once-in-a-decade heat wave, in the Tokyo region is 3.1% for July and 4.8% for August, whereas the figures elsewhere stand above 5% for both months, according to the ministry.

The reserve capacity ratio below 3% risks power shortages and blackouts.

Last year, the highest temperatures for the season since record-keeping began scorched much of eastern Japan for a week in June, prompting the government to ask citizens to cut power use as much as possible.

The government has not implemented any special measures for June, but it is monitoring power generators' operations and electricity demand this month, an official at the Ministry of Economy, Trade and Industry said.