(ATTN: ADDS more info in paras 6-9, 12)
SEOUL, March 27 (Yonhap) -- South Korea's presidential office Cheong Wa Dae said Tuesday that it has not yet identified a top North Korean official currently in Beijing, while noting that it is leaving "all possibilities" open.
News reports have said that a high-level Pyongyang official, possibly leader Kim Jong-un, appears to have arrived in the Chinese capital by train.
"We are carefully watching the situation concerning things that are currently happening in Beijing, with all possibilities in mind," a Cheong Wa Dae official told reporters, declining to be named.
He added that an improvement in relations between Beijing and Pyongyang is a "positive signal" ahead of the summits between the two Koreas and between the United States and the North, planned for next month and May, respectively.
"We already knew about the movement of the North Korean side a few days ago and have carefully been watching the related situation. ... But we have not confirmed yet who has traveled to Beijing," the official said.
Analysts here said that North Korean leader Kim aside, Kim Yo-jong, his younger sister, or Choe Ryong-hae, a vice chairman of the Central Committee of the ruling Workers' Party, could visit Beijing.
"We cannot confirm concrete details," the Cheong Wa Dae official said in response to a question of whether Seoul has contacted Beijing for confirmation on the North Korean official in question.
"Even if we have come to know (the official's identity), we cannot disclose it first," he added.
He, in addition, said that Seoul is exchanging related information with Washington.
The visit by an unidentified Pyongyang official came as China is expected to take steps to improve ties with its wayward ally, the North, ahead of the inter-Korean summit and the Washington-Pyongyang summit.
Observers said that Beijing may be increasingly wary of it losing leverage over Pyongyang, as their bilateral relations have soured in recent years, due to the reclusive state's repeated provocations and its stern reaction to them.
The worst scenario for Beijing would be Pyongyang falling into Washington's sphere of influence amid the intensifying Sino-U.S. rivalry for regional primacy, analysts said.