UNITED NATIONS — A substance found at a U.N. weapons inspectors’ office last month and suspected of being a chemical warfare agent appears to be a nontoxic solvent, a U.N. official said yesterday.

The material was found August 24 at a U.N. office in Midtown Manhattan in inventory files with a label that indicated it could be phosgene, a chemical substance used in World War I weapons. It had been in the files for 11 years and was only identified when officials checked the inventory number against the many records in the vast archives.

U.N. and American officials said after the discovery that the material posed no threat to anyone’s health or safety. However, it was removed by a team of hazardous materials experts from the FBI and New York City police and taken to a laboratory for testing.

Preliminary results indicate the substance was a nontoxic solvent, not the chemical agent phosgene, the U.N. official said.

“If it turns out to be something that was mislabeled, we’ll need to find out why it was mislabeled,” said the official, who spoke on condition of anonymity because the final results have not yet returned from the lab.

The United Nations has launched an investigation into how the substance ended up in the files for so long without anyone knowing what it was.

The inventory records indicated the material was from a 1996 excavation of the bombed-out research and development building at Iraq’s main chemical weapons facility at Muthana, near Samarra. The entire facility was extensively bombed during the 1991 Gulf War, said Ewen Buchanan, a spokesman for the U.N. inspection agency.

The records showed it had been stored in the files at the U.N. Monitoring, Verification and Inspection Commission, or UNMOVIC, for the last 11 years.

The agency and its archives — including the suspect material — had been in an office at U.N. headquarters until moving to its current site in Midtown Manhattan about three years ago, he said.