However, Danny Coulson said the devices were fired hours before the blaze began on April 19, 1993, and were not to blame for the fire that consumed the compound with David Koresh and more than 80 followers inside.
"The fire did not start there. That's a lot of nothing," he said in Tuesday's Dallas Morning News.
The issue of whether the FBI used pyrotechnic devices is a major focus of an ongoing inquiry by the Texas Rangers and a key allegation in a pending federal wrongful-death lawsuit filed against the government by surviving Davidians and families of those who died.
The federal government consistently has disputed accusations that the FBI started the fire. Independent investigators concluded the fire began simultaneously in three separate places.
FBI bugs recorded Davidians discussing spreading fuel and planning a fire hours before the compound burned. Arson investigators also found evidence that gasoline, charcoal lighter fluid and camp stove fuel had been poured inside the compound.
Government officials have maintained the FBI used only nonflammable devices to get tear gas into the compound because of fears that pyrotechnic grenades might spark a fire in the wooden structure.
The statement by Coulson, founding commander of the FBI's hostage rescue team and a deputy assistant FBI director at the time of the Waco incident, marks the first time any government official has publicly contradicted those claims, the News reported.
A spokesman with the U.S. Justice Department again denied Monday that any pyrotechnic devices were used.
"We are aware of no evidence to support the notion that any pyrotechnic devices were used by the federal government on April 19," Justice Department spokesman Myron Marlin told the newspaper. "We've said that all along."