
North Korean troops have shot dead three compatriots who were trying to cross the border into China, according to a South Korean activist.
The report comes as North Korea moves to tighten border controls after the death of the leader, Kim Jong-il.
Border guards killed the men in their 40s who were crossing the Yalu river from the northern border city of Hyesan on Saturday, Do Hee-youn, who helps refugees from the North, said.
"People waiting at the Chinese side across the river to help the three defect saw the scene. The guards took with them the bodies which were lying on the ice," Do told AFP news agency on Tuesday, citing sources in China's border county of Changbai.
South Korea's intelligence service said it could not immediately confirm the reported shootings.
Activists say the North has intensified patrols along its border to try to prevent defections in the wake of Kim's death on December 17.
They fear a tougher crackdown during the politically sensitive transition which sees Kim Jong-un, the son of the late leader, take power as supreme commander of the military and the ruling party leader.
"They are trying to let people know that those trying to flee will be shot dead right away," Do said, citing sources in the North who communicate via mobile phones smuggled in from China.
About 23,000 North Koreans have fled repression or hunger in their homeland for South Korea since the 1950-1953 war, the vast majority in recent years.
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