The number of foreign tourists in September surged 31.7 percent over the previous year to 867,000, breaking the record for the month, according to the Japan National Tourism Organization.

But the number of South Korean visitors fell below 200,000 for the first time this year, apparently due to concern over the reported leaks of radioactive water at the crippled Fukushima No. 1 nuclear power plant, JNTO officials said Wednesday.

While the September total for South Korean visitors came to 164,500, up 12.9 percent, the growth marks a slowdown from the year-on-year growth rates in the period from January to July, which ranged between 28.6 and 45.5 percent.

In the previous month, South Korean visitors grew 6.9 percent — the slowest rate of the year.

The Japanese government is worried that radiation concerns harbored by the South Koreans may hamper efforts to achieve its goal of 10 million foreign visitors a year.

The tally for the first nine months was 7,731,000, with South Koreans accounting for 25 percent. Since no sharp recovery is expected in South Korean visitors, the organization plans to encourage people in Southeast Asia to visit Japan for the Christmas holidays.

In the reporting month, the highest number of tourists came from Taiwan at 206,800, an all-time high for the month, leaving South Korean visitors second overall. China came in third with 156,300 visitors, up 28.5 percent for another all-time high for the month.

The Chinese number marked the first rebound in a year since last October, when year-on-year numbers fell because of the bilateral clash over the Japanese government’s effective nationalization in September 2012 of the Senkaku Islands in the East China Sea. China and Taiwan also claim sovereignty over the isles.

Visitors from Hong Kong and Thailand came to 55,400 and 29,300, respectively, also setting all-time highs for the reporting month.