A ranking North Korean embassy official in Beijing has defected, South Korea's Yonhap news agency has said, while a separate report suggested two embassy staff had sought asylum with the Japanese mission in the Chinese capital.
Yonhap, quoting an anonymous source "Familiar with Pyongyang affairs", said the official - stationed in the Beijing embassy but attached to the North Korean health ministry - had disappeared with his family in late September.
The source said the official was responsible for sourcing medical supplies for a clinic in Pyongyang that caters to North Korean leader Kim Jong-Un and his family.
The newspaper cited an anonymous source as saying the two officials were not diplomats, but attached to a North Korean government office.
"There's no truth in the reports that North Korean asylum seekers contacted the Japanese embassy, and we're not aware of any situation involving North Koreans hoping to defect to Japan," Suga told a regular press conference.
The North has been rocked by a number of high-level defections, most recently that of its deputy ambassador to Britain who fled to the South in a major propaganda victory for Seoul.
In a speech last Saturday to mark Armed Forces Day, South Korean president Park Geun-Hye made a direct appeal to more North Koreans to abandon their country.