A team of Rockville scientists announced plans yesterday to create a stripped-down, single-cell microbe that could become an energy source, a tool to combat global warming or a biological weapon.

Geneticists J. Craig Venter and his partner, Hamilton O. Smith, hope to develop a synthetic chromosome by removing the genetic material from a tiny organism and inserting manmade genetic material.

If the cell survives, it could be genetically adapted for use as a hydrogen-based fuel, an agent for cleaning carbon emissions from the air or a tool to fight biological weapons, according to the researchers.

The three-year project will be conducted by their Institute for Biological Energy Alternatives, a not-for-profit organization formed by Venter, a maverick who set up a private company to compete with government scientists in the race to map the human genome two years ago.

Venter left the Celera Genomics Group in January in a disagreement over the direction of the company.

Smith, who is directing the work at IBEA, won the Nobel Prize in 1978 for his accomplishments with enzymes and molecular genetics while at the Johns Hopkins University.

The work is being funded with a $3 million grant from the Department of Energy.

The project, reported in yesterday's Washington Post, was initially described as an effort to create a new life form. But yesterday some scientists said the team's work - described in a news release posted on the IBEA Web site - would not create a new life form, but rather add genetic material to an existing organism.

Eckard Wimmer, a virologist at the State University of New York at Stony Brook who created a polio virus from scratch this summer, compared the project to stripping down a car and rebuilding it.

"It's like taking out the parts of a car, stripping it down to its basic elements. You may have changed it, but you still have a car," Wimmer said.

Jeff Sherwood, a spokesman for the Department of Energy, also said yesterday that the grant approved in September had nothing to do with creating life forms.

"Our goal isn't to create a new form of life. If this research could be said to create a new form of life, it will do so in the same way that scientists in thousands of laboratories routinely delete or insert genes into microbes, mice or food crops," Sherwood said. "This research is fundamentally no different."

A spokesman said Venter was traveling yesterday and unavailable for comment. Smith also could not be reached.

But in a news release, Venter said the group has hired 10 researchers and scientists and plans to hire 15 more to complete the project.

Venter's statement said the work is aimed at the search for new sources of energy, reducing pollution that causes global warming and undertaking "genome engineering to better understand the evolution of cellular life."

IBEA plans to work with Mycoplasma genitalium, a bacteria found in human genitals. It was selected because research conducted by Venter's group in the 1990s showed that the organism needed a relatively small number of genes - about 300 - to survive. People, by contrast, need up to 50,000 genes to survive.

Work will begin in IBEA quarters at the Maryland Information Technology Center in Rockville. But Venter's statement said IBEA would eventually move to the same Rockville campus that is home for the Institute for Genomic Research, another Venter facility established for genetic research.

The unknown impacts of creating a partially manmade organism have raised concerns among ethicists.

They also expressed concerns that the organisms' ingredients could become the basis for a new generation of biological weapons.

"I favor pursuing it because it's potentially such a powerful tool, but we have to keep an eye on it and restrict it and control it," said Arthur L. Caplan, a bioethicist at the University of Pennsylvania who co-chaired a panel of ethicists recruited by Venter to review the proposal.

Venter said the new cell would be designed so that it is incapable of infecting people or surviving outside a laboratory, according to the Post.

Caplan said the 12-member ethics panel included a priest, a rabbi and two ministers. They met eight to 10 times over a year and concluded that the work should proceed because of its potential benefits to mankind, he said.

"One core issue is, is it playing God to make a life form? I don't think so," said Caplan.

But he said the research findings might have to be kept secret because of concerns that the new organism could be altered into a biological weapon.

"It raises many tough issues and questions: The possibility of weapons use, where you publish, or whether you publish at all," he said.

The idea of creating genetically altered life forms is not new.

Genetically altered microbes have been cleaning up oil spills since the 1970s. When gene splicing was invented in 1973, it immediately sparked debate about whether human-designed pathogens would be more harmful than natural ones.

The Associated Press contributed to this article.