BEIJING - China must urgently reform its food safety system to increase oversight and hold businesses responsible for their products, United Nations officials said Wednesday.

The call, issued along with a UN report on China's food safety, comes as China is dealing with a scandal over melamine-tainted milk that has sickened tens of thousands of children and been blamed in the deaths of four infants.

Authorities say the industrial chemical, normally used in plastics and fertilizer, was added to watered-down milk to make the products seem higher in protein when tested.

"The national system needs urgent review and revision," UN Resident Coordinator in China Khalid Malik said.

China's food exports have been increasing at a rate of over 20 per cent year-on-year to reach US$27 billion in 2006, the report said.

"The only way to rebuild confidence is to put in place an effective food control system from farm to table, and we hope they do that," said Tony Hazzard, a World Health Organization adviser on food safety who presented the report.

China needs a unified regulatory agency, the report said, and a place consumers can go for reliable information. The task is now split between different government agencies, creating uneven enforcement that is further complicated by numerous laws.

Such a scattered approach and a lack of communication slowed down the response to the tainted milk scandal, said Jorgen Schlundt, director of the department of food safety at the WHO in Geneva.

The report also said Chinese businesses need to take responsibility for their supply chains. China's largest dairies in Inner Mongolia said last week they were shifting to take control of sourcing milk from cows, rather than from small scattered milk collection stations that have been blamed for the addition of melamine.

"Absolutely, the burden should be on the businesses. They are the ones making the profit. They have the due responsibility," Hazzard said.

Many of the largest companies whose products have been recalled, like Inner Mongolia-based Yili Industrial Group Co. and Mengniu Dairy Group Co., did not have government inspections and did not test for melamine before the problem became public last month, even though adding the chemical to fool protein-level tests was known to be a widespread practice in the dairy industry.