Face transplants are technically possible and could arguably be less difficult than reattaching a severed finger, surgeons said, but they called for more research into the risks involved before they were attempted.
The microsurgical skills needed for a face transplant already are well established, according to a report by the Royal College of Surgeons of England.
But too little is known about the psychological impact it would have on the recipient or the donor family, the ethical issues or the long-term risks of immunosuppressive drugs that would have to be taken for life to prevent the immune system from rejecting the new face.
"We do not feel that the time is appropriate at the moment," Sir Peter Morris, president of the Royal College of Surgeons, told a news conference Wednesday.
In the detailed report on the feasibility of face transplants, Morris and a panel of experts said the surgery would be a major breakthrough for people who have been disfigured.
But Morris stressed the importance of the psychological and ethical implications and said lifetime use of immunosuppressive drugs would increase the risk of certain types of cancer and other illnesses.
Dr. John Barker, associate professor of surgery at the University of Louisville in Kentucky, said his team was ready to perform the world's first face transplant.
"We need to get across the complexities of this medical advance and dismiss the myths that have been reported -- for example, the first face transplant recipients will not necessarily look like the donor," he said.
Transplanting the skin and underlying soft tissue from one individual to the facial structure of another would give an appearance that would be different from the donor and the recipient, Barker added in a statement.