North Korean authorities are boosting their efforts to crack down on would-be defectors to China as well as their families.

Japan's Sankei Shimbun newspaper, citing unidentified sources, said Wednesday that North Korea had begun a large-scale manhunt to find potential defectors holed up near the country's border with China.

The newspaper alleged that North Korean leader Kim Jong-il had ordered the crackdown and that a large number of Pyongyang officials have been mobilized for related operations.

Sankei claimed that the rare action was prompted by a report submitted to the North Korean leader.