China’s thirst for oil makes it by far Sudan’s biggest trading partner. While oil is shipped east, arms and ammunition destined for Darfur’s scorched battlegrounds arrive in return, putting Beijing firmly in the sights of human rights activists.

Tim Hancock, Amnesty International’s campaigns director, said: “China’s huge investment in Sudan plays a vital role in the country. Targeting China is a key way to influence the government of Sudan.”

Almost two thirds of Sudan’s oil exports go to China in a deal estimated at more than £1 billion a year. China’s fingerprints are all over the Sudanese capital, Khartoum.

The city’s new bridge across the Nile was built by Chinese engineers and is adorned with a single flag, bearing the colours of its communist sponsors.

Billions of dollars of Chinese money have been invested in infrastructure projects, including oil refineries, pipelines, dams and roads.

Chinese language schools are opening to help Sudanese looking to get on in the yuan-fuelled economy.

The relationship between the two countries was strengthened further last year with the visit of President Hu Jintao. He promised to write off $80 million in debt and threw in an interest-free loan of $13 million for a new presidential palace.

His largesse means that Khartoum has the feel of a boom town. New hotels, office blocks and golf courses are being built.

“There are Malaysians, Arabs and Libyans here investing money, but still nothing on the scale of the Chinese,” said a Khartoum-based analyst speaking on condition of anonymity.

At the same time as Chinese money pours in, the country has emerged as a sanctions-busting supplier of weapons.

Two Chinese-built Fanfan fighter jets have been stationed in Nyala, the capital of south Darfur. They were spotted bombing rebel targets near Haskanita last September.

Many Janjawid militiamen in Darfur sport Chinese-made AK47 rifles and boast that their weapons are superior to older Russian models.

Amnesty says imports of arms and ammunition were worth $24 million in 2005. A further $59 million of aircraft and parts also arrived that year.

For now the killing continues. Khartoum launched a fresh offensive in west Darfur last week. The United Nations says 12,000 people fled into Chad after villages were bombed by Sudanese armed forces.

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