North Korea and China have stepped up crackdown on defectors after the purge of North Korean eminence grise Jang Song-taek, virtually blocking their escape routes.
Defectors said fewer than 10 North Koreans are currently held in a detention center in Thailand. Normally, some 50 to 100 defectors are held in Thailand at any time because the country is an important stopover on the escape route.
But recently many defectors have been arrested in Kunming, on the Chinese side of the border with Laos.
"Chinese police have intensified searches on the major escape routes such as the China-Laos and China-Vietnam border areas in Yunnan and Guangxi provinces and the China-North Korea border areas in Liaoning and Jilin provinces," an activist helping defectors said.
He added defectors and their helpers in Hunchun, Yanji, and Dandong have fled to inland China.
The crackdown comes amid rumors that scores of North Korean officials earning hard currency under Jang's supervision as well as hundreds of North Korean security forces defected to Hunchun in Jilin province.
Other rumors say trade officials under Jang's supervision who were in Hunchun and Yanji to lure foreign investment to the casino industry went into hiding in China when they heard of his ouster.
The regime is drastically tightening security in the border areas and elsewhere in the wake of the purge and ahead of the second anniversary of former leader Kim Jong-il's death.