Two monkeys named Zhong Zhong and Hua Hua have become the first non-human primates to be cloned using the same technique as Dolly the sheep 20 years ago - somatic cell nuclear transfer.

The long-tailed macaques were born several weeks ago in a laboratory in China.

The scientists behind the cloning said the monkeys would be useful for studying diseases, including cancers and immune disorders.

But critics said the research raised ethical concerns and could potentially bring the world closer to human cloning.