China said Tuesday it would send observers to its close ally Sudan, where voting on an independence referendum for the south of the country is due to begin at the weekend.
"At the invitation of both sides, China will send an observation mission for the referendum," foreign ministry spokesman Hong Lei told reporters.
China — which does not elect its leaders by popular vote — is a key supporter of Sudan's President Omar al-Bashir, who is wanted by the international criminal court for war crimes in the Darfur region.
It is also a military supplier and the biggest buyer of the country's oil.
"China hopes that the referendum will be held in a fair, free, transparent and peaceful atmosphere, and all parties involved should be committed to peace and stability in Sudan," Hong said.
Almost four million people have signed up to vote in southern Sudan's referendum, which is due to begin on Sunday and last until January 15, organisers said Monday.
North and south Sudan signed a peace deal in 2005 after a devastating 22-year civil war, which included holding a referendum on whether the south secedes or remains part of a united country.
China had previously sent observers to Sudan when it held its first multiparty elections in 24 years last April, which led to Bashir's re-election.
China congratulated Mr Bashir for a poll victory marred by opposition boycotts, allegations of fraud and questions from European election monitors over transparency.