Both shared a flight with senior Chinese Communist Party official Wang Jiarui, who arrived in the Chinese capital from Pyongyang where he had met with North Korean leader Kim Jong Il and discussed the resumption of the stalled six-party talks.
Kim, a vice foreign minister, is North Korea's top nuclear envoy in the six-party talks and is seen as one of the main architects behind the country's nuclear policy.
Ri is the director general of the American Affairs Bureau in the North Korean Foreign Ministry.
It was not immediately clear why the two senior diplomats are in Beijing.