SEOUL - TIGHTER border controls slashed the growth rate of North Korean defectors arriving in the South by more than half last year, even though the number of defectors rose to a new record.

A government agency said on Monday slightly more than 2,800 North Korean defectors arrived in the South last year, up by 10.4 per cent from a ago, but that figure compared to a 26 per cent increase in 2007.

Almost all North Korean defectors leave the impoverished state across its border with China and then seek asylum in a third country.

China calls the defectors economic refugees and forcibly returns them to North Korea where they face sentences in brutal prison camps.

Aid agencies who help North Koreans seek asylum have told Reuters the North increased its penalties on would-be border crossers after leader Kim Jong-il's suspected stroke in August.

The aim was to squelch any suspicion of a leadership vacuum by showing North Korea's citizens the central government was well in control.

A South Korean government official said China also clamped down on its border ahead of the Beijing Olympics in August.

The North's border with China is several hundred kilometres long and there are many places where North Koreans can cross with relative ease.

The North's border with the South is one of the world's most militarised and crossings by defectors are rare.

More than 15,000 North Koreans have defected to the South since the end of the 1950-53 Korean War, according to the Unification Ministry. -- REUTERS