Hundreds of couples have volunteered for an experiment to create the first cloned children despite strong religious and scientific opposition.
Since the international team said in January it would work to produce the first human clone, between 600 and 700 couples have put themselves forward and the number is rising rapidly, U.S. doctor Panayiotis Zavos said.
"Interest has come from all over, from Japan to Argentina, from Germany to Britain," he told reporters after saying his team was ready to start cloning in the next few weeks, principally to help infertile couples bear children.
And he deflected mounting criticism of his plans, saying people would eventually get over opposition to human cloning.
"Historically this is normal but once the first baby is born and it cries, the world will embrace it," he said.
"Now that we have crossed into the third millennium, we have the technology to break the rules of nature."
But the proposal has come under fire from mainstream scientists and religious groups. Yesterday, Father Gino Concetti, a moral theologian whose views are thought to reflect those of Pope John Paul, reiterated the Vatican's stance.
"These proposals contradict the truth of mankind, man's dignity, man's rights ... especially the right to be conceived in the human way," he said.
Italian team member Severino Antinori, who gained notoriety by helping a 62-year-old woman give birth, also sought to dispel the flood of disapproval.
"Cloning may be considered as the last frontier to overcome male sterility and give the possibility to infertile males to pass on their genetic pattern," he said.
Scientists have warned that 97 per cent of animal cloning attempts have been unsuccessful and that those embryos which survive to birth are often deformed.
Dr Ian Wilmut, who created Dolly, the world's first cloned sheep, said it had taken 277 attempts to get it right.
The team said they would start work within weeks but would not say where they will set up their cloning laboratory for security reasons. When the team announced their plans in January, they said they would work in a Mediterranean country.
Last year, Britain proposed allowing human cells to be cloned for research purposes while other European countries including Spain and France have banned human cloning altogether.