Two monkeys have been cloned using the technique that produced Dolly the sheep.
Two identical long-tailed macaques named Zhong Zhong and Hua Hua, cloned using the same technique that produced Dolly the sheep were born in a Chinese lab several weeks ago.
Ethical concerns have been raised by critics who are sceptical about human cloning, but scientists say monkeys who are genetically identical to us will be useful in research regarding human diseases.
A spokesman from the Chinese Academy of Sciences Institute of Neuroscience, Qiang Sun, said the cloned monkeys will be useful as a model for studying diseases such as certain cancers as well as metabolic and immune disorders.
"There are a lot of questions about primate biology that can be studied by having this additional model," he said.
Currently, the monkeys are being bottle fed and are said to be growing normally. Researchers expect more macaque clones to be born over the next few months.
However, Prof Robin Lovell-Badge of The Francis Crick Institute, London, says the technique used in this instance remains "a very inefficient and hazardous procedure".
"The work in this paper is not a stepping-stone to establishing methods for obtaining live-born human clones," he said.
Prof Darren Griffin of the University of Kent said, "Careful consideration now needs to be given to the ethical framework under which such experiments can, and should, operate," but that this approach may be useful in understanding human diseases.
Dolly made history 20 years ago after being cloned. It was the first time scientists had been able to clone a mammal from an adult cell, taken from the udder.
20 years ago, at the Roslin Institute in Edinburgh, Dolly the sheep was the first mammal to be cloned using the same somatic cell nuclear transfer technique (SCNT), since then, many other mammals, from cattle to pigs, dogs, cats and mice have been cloned.
The SCNT process requires the transferral of healthy DNA from the nucleus of a cell to a donor egg cell that has had its own DNA removed. From there, with a little assistance, it develops into an embryo that is implanted in a surrogate animal. In this case, the first non-human primates.
Zhong Zhong was born eight weeks ago and Hua Hua six weeks ago. They are named after the Mandarin term for the Chinese nation and people. The two monkeys were the result of 79 attempts, while two others that were cloned from a different type of cell failed to survive.
Dr Sun said: "We tried several different methods, but only one worked. There was much failure before we found a way to successfully clone a monkey."
Dr Sun's co-researcher, Dr Muming Poo, said: "We are very aware that future research using non-human primates anywhere in the world depends on scientists following very strict ethical standards."
The scientists say they followed strict international guidelines for animal research, set by the US National Institutes of Health.