Chinese-made bullets and aircraft bought from Russia are used to commit rights violations in Sudan's Darfur under an ineffective UN arms embargo, Amnesty International said on Thursday.
The London-based rights watchdog aired similar concerns five years ago but its latest report comes after "a new wave of fighting" between opposition groups and government forces over the past year.
"This has included targeted and ethnically motivated attacks on civilian settlements, and indiscriminate and disproportionate aerial bombings that have contributed to the displacement of an estimated 70,000 people from their homes and villages," Amnesty said.
It said China and Russia continue to supply weapons and munitions to Sudan despite "compelling evidence" they will be used against civilians in Darfur, the western region where rebel groups rose up against Khartoum's Arab-dominated government in 2003.
The exports also include attack jets, air-to-ground rockets and armoured vehicles, Amnesty said.
"China and Russia are selling arms to the government of Sudan in the full knowledge that many of them are likely to end up being used to commit human rights violations in Darfur," said Brian Wood, an expert on military and policing for Amnesty.
As an example, the group cited a December 1 incident in which the paramilitary Central Reserve Police carried out a "looting raid" in which one man was shot dead and six people were wounded in the Zam Zam camp for people displaced by the Darfur conflict.
Witnesses told Amnesty they found bullet cartridges marked with Chinese codes indicating their transfer to Darfur after the arms embargo began in 2004.
Amnesty said fighting in Darfur has been accompanied by a repeated pattern of airborne attacks on civilian and military targets using Sukhoi-25 jets, Mi-24 gunships and Antonov transport planes used as "rudimentary but effective bombers."
Sudan received 36 new Mi-24 helicopters from Russia between 2007 and 2009, a number which "undoubtedly" compensates for those lost during Darfur operations last year, Amnesty said.
"Their continual replacement by the Russian Federation makes it possible for such attacks to continue," despite a UN prohibition on airstrikes, it said.
Attacks on civilian settlements and property by armed opposition groups in Darfur have also persisted, in violation of international law, the group added. But it could not verify the origin of the rebels' military equipment -- much of which the rebels claimed to have captured from government forces.
Next week the UN Security Council, which China and Russia are veto-wielding members of, will again consider the Sudan sanctions, and governments will resume talks on a future arms trade treaty, Amnesty said.
"The Darfur conflict is sustained by the constant flow of weapons from abroad. To help prevent further serious violations of human rights, all international arms transfers to Sudan should be immediately suspended and the UN arms embargo extended to the whole country," Wood said.
The Darfur case highlights the need for an effective arms trade treaty that would compel governments to stop weapons transfers where there is a substantial risk they would be involved in serious rights violations or war crimes, Amnesty added.
Sudan's President Omar al-Bashir is wanted by the Hague-based International Criminal Court for crimes against humanity, war crimes and genocide allegedly committed in Darfur.
Khartoum's ministry of foreign affairs had no comment on the Amnesty report.
The Russian embassy could not immediately respond to a request for comment, and a spokesman for Beijing's mission could not be reached.
The UN estimates at least 300,000 people died as a result of the conflict in Darfur, with about 300 killed in clashes last year.
Sudan puts the overall death toll at 10,000.