China has demanded the handover of four North Korean asylum seekers who are being sheltered in South Korea's consulate in Beijing.

But a South Korean Government official said the four would not be given up unless China first agreed to let them travel to Seoul.

The case is the most diplomatically complicated so far in a string of asylum bids by North Koreans fleeing the impoverished country by taking refuge in foreign missions in China.

Successful refugee bids may be prompting others to try too

China has let 38 North Koreans leave for South Korea in the last two months.

But on Tuesday, China appeared to adopt a harsher line when Foreign Ministry spokesman Kong Quan called for the latest group of asylum seekers to be given to China to deal with.

"We believe that according to international and Chinese laws, foreign embassies have no right to grant asylum to citizens of a third country," he said.

South Korea's official Yonhap news agency replied that Seoul hoped the four would be dealt with on humanitarian grounds, and would be sent where they wanted to go.

The latest case involves three North Koreans who slipped into the South Korean consulate last week, and a fourth who joined them on Monday.

Bad timing

Correspondents say the latest case is complicated because it will pressure China into choosing whether to offend North or South Korea.

High-profile North Korean escapes to South via China

June 2001 Family of seven who sheltered in UN office in Beijing March 2002 25 people who entered Spain's Beijing embassy May 2002 Five people from US and Canadian diplomatic sites May 2002 Five relatives taken by Chinese police from Japanese consulate

It also comes at a difficult time for South Korea, which had hoped to keep asylum issues out of the news as it prepares to co-host football's World Cup.

The last known case where a North Korean sought asylum in the south having entered a South Korean mission in China was in 1997.

That case, which involved North Korea's top communist theorist and party secretary Hwang Jang-Yop, took seven weeks of negotiating before he was allowed to travel to Seoul.

In recent years, tens of thousands of North Koreans have fled famine and repression to live in China.

China has a treaty with its ally North Korea which requires it to send them back to the hard-line communist state.

But in recent, high-profile cases, China has preferred to let asylum seekers travel to Seoul via third countries.

It has tried to stem the tide by increasing security around embassies and consulates, ringing the compounds with barbed wire and posting additional guards.