China has frozen remittances to North Korea and halted imports of North Korean coal ahead of UN Security Council sanctions on Pyongyang over its nuclear test and rocket launch.
On Wednesday, banks in the Chinese border town of Dandong suspended all money transfers to North Korea at the instruction of Chinese financial authorities.
"Our bank headquarters has instructed us to suspend all remittances to the North," a staffer with a state-run Chinese bank said. "Yuan remittances were possible until late last month, but now remittances in all currencies are frozen."
China already froze dollar remittances after the North's previous nuclear test in 2013.
The move makes it impossible for North Korean trade officials and hard-currency earners in China to send money home through official channels.
China also halted imports of North Korean minerals through Dandong on Tuesday, the Nihon Keizai Shimbun quoted a trade official as saying.
On Monday 130 North Korean trucks crossed the bridge linking Dandong with Sinuiju in North Korea and passed the Dandong customs checkpoint, but on Tuesday their number had fallen to 70, it said.
A Chinese customs official told the Japanese daily that the North appears to have hurried to transport as much coal as possible before the ban was imposed.
Once the UNSC adopts a fresh round of sanctions, other Chinese ports will also ban imports from the North, the paper added
Europe has also been ratcheting up pressure on the North since its nuclear test.
Thomas Händel, the chairman of the European Parliament Committee on Employment and Social Affairs, said North Korean workers are suffering from "extreme forms" of exploitation in member state Malta.
"Such forms of exploitation are shocking and cannot be tolerated in the European Union," he added.
Händel recently wrote to the International Labor Organization and human rights and labor agencies of the European Union, calling for action against the exploitation.
About 50,000 North Koreans earn hard currency for the regime around the world. Some 1,000 work in the EU, 93 of them in a Chinese-owned factory in Malta, the Telegraph reported quoting the European Alliance for Human Rights in North Korea.