Immigration authorities have asked the embassies of four Asian countries and Taiwan's representative office to promote voluntary repatriation of their nationals staying in Japan illegally, Justice Ministry sources said Wednesday.

Faced with an increasing number of foreign nationals illegally staying in Japan, the ministry's Immigration Bureau made the request to the embassies of China, Indonesia, the Philippines and Thailand, as well as the Taipei Economic and Cultural Office in Japan, which functions as Taiwan's de facto embassy, the sources said.

The number of such illegal residents came to about 63,000 as of Jan. 1, with the biggest number coming from South Korea, with around 13,000, followed by China, according to the bureau.