A refugee was shot dead by North Korean border guards last month after reaching Chinese soil in a strengthened crackdown on escapees, a South Korean activist said Monday.

"During my trip to a border area on October 22, I witnessed a man shot to death after arriving in China," Kim Yong-Hwa, head of the North Korea Refugees Human Rights Association of Korea, told AFP.

The man in his 40s was apparently shot by the North's guards from near the northern border city of Hyesan and died in front of Chinese soldiers, he said.

"After a sound of shooting across the river, I saw him groaning and crawling on the ground. Several Chinese soldiers were there but did not care," Kim said.

The man struggled to get to his knees but then died, Kim said. "My tour guide recorded his last moments with a mobile phone."

The shooting of an escapee after he had reached China formed part of a wider crackdown, Kim said.

"North Korea has reinforced barbed wire, while border guards are now headed by elite cadres with a good family background," he said, adding that China was also strengthening the wire on its side.

The activist said the North had stepped up a clampdown on border crossing as Kim Jong-Un, the son of leader Kim Jong-Il, cemented his status as leader-in-waiting.

It was the second such report this year. In January, the South's Chosun Ilbo newspaper reported that North Korean border guards shot dead five refugees after pursuing them across the frontier into China the previous month.

That incident was also said to have happened near Hyesan.

Chosun Ilbo said Kim Jong-Un had ordered soldiers to shoot anyone trying to cross the border without permission.

Some 21,000 North Koreans have fled to the South since the end of the 1950-1953 war to escape repression, poverty and food shortages.

Almost all refugees leave North Korea initially by crossing into China across the Yalu or Tumen border rivers, but they face repatriation by Beijing if they are found.

Thousands hide out in China, while others travel on to third countries before flying to South Korea.