Chinese authorities have detained two Japanese nationals on suspicion of spying, Japan’s foreign ministry said Wednesday. The news of the detention was first reported by Japanese local newspaper Asahi Shimbun.

One man was reportedly detained in May near military facilities in China's coastal Zhejiang province and the other near the border with North Korea about the same time, Japan’s media reports said, citing unnamed sources. Japanese broadcaster NHK also reportedly said that it was investigating claims a third national may also have been detained.

"We are aware of the reports but would like to refrain for commenting on specific incidents," Japan's Chief Cabinet Secretary Yoshihide Suga said during a news conference, according to Reuters. "Our country in every case is making every effort concerning the safety of our citizens overseas."

Suga reportedly declined to comment on whether Japan was involved in any spying on China. "Our country is certainly not doing such things. I would like to say that this is the same with regard to all countries,” he said, according to Reuters.

Meanwhile, a senior Japanese government official said that Chinese authorities were “making an excuse to link [the two] to suspected espionage,” the Kyodo news agency reported.

The news of the detentions comes amid Japanese Prime Minister Shinzo Abe's comments Tuesday on improving ties with China.

"Already we have gone through several rounds of summit meetings and we are steadfastly moving to further develop a mutually beneficial relationship based on common strategic interests," Abe reportedly said, at Bloomberg headquarters in New York. "We need to develop our amicable relationship, a stable relationship, between Japan and China. I think both countries should make efforts to that end."

Chinese President Xi Jinping has stepped up the monitoring of foreign organizations and individuals, and also imposed strict security laws and regulations. A new counter-espionage law for closely targeting foreign spies reportedly came into force in November last year.

In 2010, four Japanese nationals, who were employees of a construction company, were detained in China on suspicion of entering a military zone in Hebei province and taking photographs without permission. They were reportedly released within a few weeks.