Washington ? Only 11 human stem cell lines are available for research, far fewer than originally estimated, the director of the National Institutes of Health reports.

The finding led to a call for lifting the restriction that President Bush placed on stem cell research.

NIH Director Elias Zerhouni, writing in today’s edition of the journal Science, says his agency is giving a high priority to research using stem cells because of the potential for treatment of diseases such as diabetes and Parkinson’s.

But Zerhouni’s review of the status of work supported by the NIH also shows that initial reports of more than 70 stem cell lines eligible for research were optimistic.

Donald Kennedy, editor in chief of the journal, contends in an accompanying editorial that development of new cell lines for research is necessary. “It is plainly not sound policy to retain the current restrictions on work” with human embryonic stem cells, he said.

Stem cells form very early in an embryo’s development. They can develop into numerous types of cells to form organs and other parts of the body. Researchers hope to use these cells to repair damaged organs and cure diseases.

But the work is controversial because the cells are taken from days-old embryos, which then die. Opponents say this is unethical.

Sources of cells are excess embryos from fertility clinics. The American Society for Assisted Reproductive Technology reported Thursday that there are 396,526 frozen embryos in storage in the United States and that 88 percent are planned for use in helping families have children in the future.

Obtaining stem cells for research has led to studies into the potential of cloning embryos, a process also criticized by opponents.