North Korea recently replaced all officers at the largest customs office on its border with China as part of moves to solidify the power base of the country’s next leader Kim Jong-un, Radio Free Asia said Wednesday.

“In addition to the Sinuiju city officials’ inspection early last month, Pyongyang’s central party authorities came down to scrutinize the Sinuiju customs office,” a source in the Chinese border town of Dandong was quoted as saying by the U.S. broadcaster.

“I heard that most of the customs officers in Sinuiju including the chief were replaced.”

The shake-up of customs officers in Sinuiju led to a stricter inspection of all vehicles passing through the border, RFA said.

By Kim So-hyun (sophie@heraldcorp.com)