A "small number" of North Koreans who had taken refuge in South Korea's Embassy in Beijing for months since fleeing their impoverished country were allowed fly to Seoul around the time of Chinese President Xi Jinping's state visit to South Korea in early July, Seoul officials said Thursday.

The North Koreans, whose number is believed to be fewer than four, had been a thorn in Seoul-Beijing relations since they entered the South Korean Embassy in Beijing seeking political asylum.

China, however, decided to allow the North Koreans to fly to Seoul around the time Xi began a two-day state visit to South Korea on July 3 for summit talks with President Park Geun-hye, a South Korean presidential official said.

A South Korean intelligence official also gave a similar account.

The move by Beijing is widely seen in South Korea as a diplomatic gift from China in connection with Xi's state visit.

"China usually resolves pending issues (with South Korea) when there is a crucial trip," said another Seoul official familiar with the matter, noting that the fate of the North Koreans holed up at the South Korean Embassy in Beijing was one of the pending bilateral issues ahead of Xi's trip to Seoul.

Multiple South Korean officials confirmed the news but none of them were willing to discuss details, including the identity of the North Koreans, the date of their arrival in Seoul and how valuable they are in terms of intelligence.

All spoke on condition of anonymity because they were not authorized to speak to the media.

The rare Chinese move came amid deepening ties between Seoul and Beijing but does not appear to reflect a fundamental change in Beijing's policy on North Korean defectors.

However, Xi's South Korea trip in July was a clear departure from China's past policy. It marked the first time that a Chinese president visited South Korea before traveling to North Korea since Seoul and Beijing established diplomatic relations in 1992.

According to South Korean activists, China has recently arrested dozens of North Korean defectors hiding in its territory in its latest crackdown apparently prompted by Pyongyang's request to find a prominent North Korean pianist who went missing in northeastern China in June.

China has launched the so-called "100-day battle" to find the pianist without success, according to activists. Some North Korean defectors in Seoul said North Korea has dispatched agents to China to try to capture the pianist, citing their contacts in the North.

As Pyongyang's key ally, China does not recognize North Korean defectors as refugees and regularly repatriates them to their home country, where they can face harsh punishment.

"These days, China trucks about 50 North Korean defectors from its immigration detention center in Tumen to North Korea's Namyang city just across the border every Tuesday," an activist said, citing an unidentified Chinese official familiar with the matter.

He did not elaborate on the official's identity for fear of possible reprisal against her by the Chinese government.

But China has allowed North Korean defectors involved in high-profile cases or those who sought refuge at South Korea's Embassy and other foreign diplomatic missions to travel to South Korea in the past, usually via a third country, to avoid international opprobrium.

Tens of thousands of North Koreans are believed to be living in hiding in China, hoping to travel to Thailand or another Southeast Asian country before resettling in South Korea, which is now home to about 27,000 North Korean defectors. (Yonhap)