North Korean businessmen working in northeastern Chinese border cities are struggling to find profitable ways to make money, hit by political ramifications following the execution of leader Kim Jong-un's uncle and a cooling Chinese economy, multiple sources close to the matter said Monday.

Since the once--powerful uncle of Kim, Jang Song-thaek, was executed in December 2013 on charges of treason, corruption and others, North Korea has gradually summoned its businessmen in China who are believed to be royal to Jang.

The high-profile execution of Jang, who had played an important role in initiating joint business projects with China, has also taken its toll on work by North Korean businessmen in the Chinese border cities of Shenyang and Dandong because it further dampens the already-fragile confidence of Chinese investors.

A source in a northeastern Chinese city, who spoke on condition of anonymity because of the sensitivity of the issue, said only about 30 percent of the North Korean businessmen have returned to China after being summoned.

The summonses are also believed to be part of efforts by North Korea to redistribute the "rights of doing businesses with China," a key source of earning hard currency, to its ruling elite, the source said.

"The replacement of businessmen loyal to Jang Song-thaek has been gradually carried out and a lot of North Korean businessmen were summoned until late last year," the source said. "Of those being summoned, only about 30 percent returned to China."

There are no official data on how many North Korean businessmen are working in the Chinese border cities.

A second source in another Chinese border city with North Korea said that about 170 North Korean businessmen in the city were replaced over the past year.

With Chinese investor confidence eroding over the North's unpredictable behavior, the new North Korean businessmen come under further pressure in building business connections with their Chinese counterparts, the second source said.

The North Korean businessmen have also felt the pinch of a slowdown in the Chinese economy, which grew 7.4 percent last year, marking a 24-year low.

A third source in the Chinese border city of Dandong said, "As demand falls and prices decline in the face of an economic slowdown in China, it is difficult for North Korean businessmen to sell goods even at lower prices."

According to data compiled by the Beijing unit of the South's Korea Trade and Investment Promotion Agency (KOTRA), North Korea's annual trade with China fell 2.4 percent from a year ago in 2014, marking the first decline since 2009.

North Korea's trade with China totaled US$6.39 billion last year, compared with $6.54 billion in 2013, the data showed.

Last year, North Korea's exports of coal to China slipped 17.6 percent from a year ago to $1.13 billion, marking the first drop in 8 years, according to the data. (Yonhap)