South Korea has asked China not to repatriate nine North Korean defectors, who were sent back to China from Laos early this week, to their totalitarian homeland, a senior Seoul official said Wednesday.

The nine North Koreans, aged between 15 and 23, were deported to China, on Monday, after being rounded up by the Lao authorities on May 10, Seoul's foreign ministry officials have said. South Korea had asked Laos to send them to Seoul after they fled from their country to the Southeast Asian nation via China last month, but Laos rejected Seoul's plea.

"Our government has asked the Chinese authorities not to repatriate the nine North Korean defectors to the North through various diplomatic channels," the official at Seoul's foreign ministry said on the condition of anonymity.

The official denied an earlier media report that the North Korean defectors -- seven men and two women -- were repatriated to Pyongyang via an Air Koryo flight on Tuesday.

"To my knowledge, the North Korean defectors are still believed to be in Beijing," the official said, adding that South Korea is trying to find their whereabouts in the Chinese capital. 

The North Koreans were flown from the Lao capital, Vientiane, to Kunming in southwest China on Monday, and they were believed to have "appropriate travel documents," according to the official.

"Because they have appropriate travel documents, the Chinese authorities' involvement in this case may be limited," the official said.

Still, there have been unconfirmed claims, raised by some civic groups in Seoul, that the nine North Koreans might have already been repatriated to North Korea.

Kwon Young-se, Seoul's new ambassador to Beijing, told reporters on Wednesday that his government "has not confirmed whether they are in Pyongyang or not," when asked about the whereabouts of the North Korean defectors.

Kwon, who is to take up the post next week, vowed to step up diplomatic efforts to prevent China from repatriating North Korean defectors to the North.

Meanwhile, a South Korean couple who helped the North Koreans in Laos were released on Monday after being held with them and returned to Seoul on Wednesday, a Seoul government source said.

"The (South) Korean couple were released on May 27 and arrived in Seoul this morning," the source said.

The ministry has set up a task force, headed by Deputy Foreign Minister Lee Kyung-soo, to handle the case, he said, adding that his government confirmed that they landed in China.

Laos has become one of the major transit points for North Korean defectors, who flee their homeland through China with the aim of eventually entering South Korea.

Tens of thousands of North Korean defectors are believed to be hiding in China, hoping to travel to Laos, Thailand or other Southeast Asian countries before resettling in South Korea, which is presently home to more than 25,000 North Korean defectors.

North Korean defectors face harsh punishments and even execution after being repatriated from China, which does not recognize them as asylum seekers, according to defectors in South Korea and human rights activists.

Related to this latest incident, non-governmental organizations have claimed that since Kim Jong-un took power in late 2011, Pyongyang has beefed up efforts to block people from fleeing the country. They said that the extraordinary move to retrieve the nine escapees from Laos, which most probably involved the North Korean embassy in Vientiane, is testament to the importance being placed by the communist country on preventing its citizens from escaping.

"There has been a spike in the number of National Security Agency operatives working in countries such as China who are tasked with capturing defectors," said Kim Yong-hwa, head of the NK Refugees Human Rights Association of Korea. He said teams of up to 150 operatives may be operating in certain regions of China.

He also claimed that it has become more difficult for North Koreans to approach the border with China due to the increased number of checkpoints. The representative also added that stricter disciplinary actions against border guards who allow people to escape has caused for a drastic increase in the amount of money to be offered as a bribe.

"Under the incumbent leader's late father Kim Jong-il, a guard would allow a person to cross over to China if he or she offered a bribe equivalent to 1 million South Korean won, but now the amount has jumped more than six-fold," Kim said. (Yonhap News)