TOKYO • China said it has arrested two Japanese citizens for suspected spying, a move likely to strain already tense ties between Asia's two largest economies.

The detentions - the first since 2010 involving Japanese on such charges - come as relations remain clouded by disputes over islands in the East China Sea and Tokyo's wartime history.

In Tokyo, Japan's top government spokesman said yesterday that the two people were detained separately in May, one in the north-eastern province of Liaoning and another in the eastern province of Zhejiang.

Chief Cabinet Secretary Yoshihide Suga said he believed they were private citizens and Japanese diplomats had "offered support". Japan does not engage in spying, he told a briefing earlier in the day.

China's Foreign Ministry said yesterday that the two Japanese were arrested "on suspicion of carrying out espionage activities".

Asked why they had been held for months without any public statement, spokesman Hong Lei told a regular briefing that China had dealt with the case "in accordance with the law".

Japan's Asahi newspaper said the two Japanese are being held on a string of charges including violating China's anti-espionage law introduced last year. One was detained near the North Korean border, while the other was picked up close to a military facility in Zhejiang province, public broadcaster NHK and the Asahi cited sources as saying. Kyodo News said both are in their 50s.

In 2010, four Japanese nationals were temporarily detained in China on suspicion of entering a military zone and taking photographs without permission.

AGENCE FRANCE-PRESSE, REUTERS