SEOUL: The number of North Korean refugees fleeing to the South fell sharply last year, officials in Seoul said, with activists citing crackdowns and tighter border controls.

A total of 1,508 North Koreans arrived in the South in 2012 -- nearly all of them via China -- down from 2,706 the previous year, the Unification Ministry said.

Activists said the North had cracked down on people trying to flee the country under new leader Kim Jong-Un, who took power following the death of his father Kim Jong-Il in late 2011.

Searches for North Koreans living in hiding in China have also been intensified in cooperation with Chinese security authorities, they added.

"Border guards are under an order from Kim Jong-Un to shoot to kill anyone who attempts to cross the (North Korea-China) border illegally," Pastor Kim Sung-Eun of the Caleb Mission told AFP.

The mission is one of several South Korean Christian evangelist groups which help North Koreans escape and resettle in the South.

Kim said the cost of getting someone out of North Korea had escalated in recent years and now stood at around 10 million won ($9,300) -- more than half of which is used to bribe border guards.

A total of 24,613 North Koreans have settled in the South since 1998, the Unification Ministry said, with around 50 percent of them unemployed or retirees struggling to make ends meet.