An Italian professor says he plans to start cloning human embryos in November.
Professor Severino Antinori told delegates at an international conference there are ways to screen out abnormal embryos.
Other researchers argued that cloning is an error-prone process.
Prof Antinori told La Stampanewspaper that 1,300 couples in America, mostly in Kentucky, and 200 in Italy are candidates for his research.
"Ours will be an experiment of therapeutic cloning for those couples who have no hope of having children," La Stampaquotes him as saying.
Because cloning would be illegal in Italy, he has said he would do the work in an unnamed Mediterranean country.
Mr Panayiotis Zavos, who runs an infertility clinic in Kentucky, also says he wants to begin cloning a human by the end of this year..
"Infertility is a disease," and couples who suffer from it need help to have children, he told the conference.
Mr Rudolf Jaenisch, of the Massachusetts Institute of Technology, was among the delegates opposing the cloning of humans: "At present there is no way to predict whether a given clone will develop into a normal or abnormal individual."
In some cases embryos grow abnormally large, Mr Jaenisch said. Others have abnormal placentas or suffer respiratory problems or heart and circulatory abnormalities.