The BBC has uncovered evidence that China is providing Sudan's government with military assistance in Darfur.
The assistance is in contravention of a UN arms embargo that requires foreign nations to stop their military assistance in that part of Sudan.
The Panorama TV programme tracked down Chinese army lorries in the Sudanese province that were exported from China to Sudan in 2005, after the arms embargo was put in place.
The lorries came from a factory in China and were consigned to Sudan's defence ministry.
The BBC was also told that China was training fighter pilots who fly Chinese A5 Fantan fighter jets in Darfur.
The UN arms embargo on Darfur requires foreign nations to take measures to ensure they do not militarily assist anyone in the conflict in Darfur, in which the UN estimates that about 300,000 people have died.
More than two million people are also believed to have fled their villages in Darfur, destroyed by pro-government Arab Janjaweed militia.
Meanwhile, thousands of people rallied in the capital, Khartoum, on Sunday to show their support for President Omar al-Bashir who's accused of war crimes by the International Criminal Court.
The prosecution reportedly plans to present evidence on Monday.
Sudan does not recognise the ICC and warns the case could stall peace talks.