China, regarded as Sudan's most powerful international ally, has been criticised for its oil investments in Sudan and its arms sales to the country.

Human-rights groups have accused Beijing of breaking a United Nations arms embargo and say Chinese military equipment has helped fuel the conflict in Darfur.

Several groups have called for protests against China's ties with Sudan during the Beijing Olympics next month.

The Chinese government however says it has played a positive role in convincing Sudan to accept a peacekeeping force in Darfur and in encouraging dialogue.

A fresh deployment of Chinese peacekeepers is expected to arrive in Darfur later this week.