Italian authorities are investigating a fertility doctor who claims to have contributed to secret human cloning projects, a police official said Monday.

Dr. Severino Antinori announced in November that three women had been impregnated with cloned embryos, saying the first would give birth in January. He would say only that he had given a "cultural and scientific contribution" to a consortium of scientists involved in the pregnancies.

Antinori has refused to comment further about the reported pregnancies. Leading fertility experts have questioned Antinori's claims.

His cloning claims were distinct from those of Clonaid, the company that said last month that it had produced the first cloned baby. Antinori dismissed Clonaid, saying it has no credibility in the science community.

Police began investigating Antinori more than two weeks ago at the request of Health Minister Girolamo Sirchia, a police official said Monday on condition of anonymity.

The official did not specify what the investigation was looking into. Italy's government has issued temporary bans on human cloning, while lawmakers have been working on passing a law to regulate artificial procreation.

Antinori was threatening to begin a hunger strike Tuesday to protest the inquiry, his spokeswoman Marica Mongardi said.

Antinori, who runs a fertility clinic in Rome, first made headlines in 1994, when he used donor eggs and hormones to help a post-menopausal 63-year-old Italian woman become pregnant.