The single largest group of defectors from North Korea is making its way to the South this week, with a few hundred already having arrived in Seoul. The defections were made possible through quiet diplomacy.

More than 200 North Koreans were flown on a chartered Asiana Airlines flight Tuesday to a military airport just south of Seoul. The passengers were quickly loaded onto buses, with curtains covering the windows, and were whisked away.

Reporters were barred from the airport during the early morning arrival. The defectors, said to be mainly women and children have been on the road for some time.

More than 200 additional defectors from North Korea are expected to arrive in Seoul on Wednesday under the same arrangement.

The South Korean government will not identify the departure point for the defectors, but diplomats and missionary groups say the country is Vietnam. Over the past few months the defectors are believed to have come across the North Korean border into China and then trickled across into Vietnam.

A foreign ministry spokesman in Seoul described the defections as a very "sensitive" issue. While welcoming the defectors, government officials appear concerned about angering the North - especially amid multi-lateral diplomacy to get Pyongyang to abandon its nuclear weapons development.

Tim Savage in Seoul is the senior analyst at the Northeast Asia office of the International Crisis Group. He says he is not surprised by the reticence of all governments involved.

"The refugee issue is very sensitive, not only for North-South relations but also for South Korea-China relations as well," he says. "And the third country also, probably Vietnam, does not want to become a hot spot for North Korean refugees either."

A spokesman for South Korea's governing Uri Party, Im Jong-seok, says "quiet diplomacy" to bring the defectors to the South should continue.

The numbers making their way from the impoverished, communist North to the capitalist South via third countries could significantly swell in the future. Unification Minister Chung Dong-young says he expects the number to exceed 10,000 in a few years' time.

Just 5,000 North Koreans have managed to make it to the South since the Korean War ended in 1953. But, South Korean media quote sources as saying tens of thousands and perhaps more than 100,000 North Koreans may currently be hiding in China.

China is obligated to repatriate them under a treaty with North Korea. But it has given tacit approval for some high profile defectors to go to South Korea, usually via another Asian country.

Officials say the hundreds arriving this week will first be taken to a facility near the capital for questioning and debriefing and then transferred to a center for a two-month orientation on how to adapt to life South Korea.

Mr. Savage, at the International Crisis Center, says South Korea would be ill prepared to handle a large number of refugees from the North. He says South Korea has cut back the amount of assistance it has been providing to recent defectors. "The South Korean government can neither afford that economically nor does it have really viable programs in place to integrate these people into South Korean society, which is the larger problem."

Activists say human rights violations are widespread in North Korea and defectors who are deported from China back to the North face several years imprisonment in labor camps and, possibly, execution.