Chinese toothpaste has been at the centre of contamination scares

The worst problems were found in canned fruit, dried fish and fruit drinks, a food inspectors' report said.

China has pledged to take action to improve its food and drug industry after a series of safety scares aroused domestic and global concern.

The US has already banned or issued warnings over several goods from China, including seafood and toothpaste.

'Quality improving'

A wide-range of products, from food and consumer goods to fertilisers and farm machinery, were tested in the first half of this year, China's General Administration of Quality Supervision, Inspection and Quarantine said in its report.

Of the goods tested, 19.1% were found to be below standard. Many of the food products had been contaminated by toxins or bacteria, or failed to carry the required labelling information, the report said.

The inspectors attempted to throw a positive light on the findings - saying that 80.9% of products had successfully passed the tests, and that quality was improving.

The inspections did not cover exported products that have caused a number of scandals this year, particularly in the US.

The problems first came to light after the deaths of dogs and cats in the US earlier in 2007.

Melamine found in wheat gluten exports from China for use in pet food was blamed, and at least 100 pet food brands were recalled.

Since then, the US Food and Agriculture department has also raised concerns about seafood products, toothpaste and the paint used in toy trains from China.