The alliance said in a statement that it dropped bombs on the convoy of Kadafi loyalists because the vehicles were "carrying a substantial amount of weapons and ammunition" which could be used against civilians.
"At the time of the strike, NATO did not know that Kadafi was in the convoy. NATO's intervention was conducted solely to reduce the threat toward the civilian population," the statement said.
NATO first struck about 8:30 a.m. on Thursday after taking note of a group of about 75 vehicles maneuvering around Surt, the statement said. The convoy was leaving the coastal city "at high speed." NATO aircraft attacked 11 of the vehicles, destroying one of them.
After that, about 20 vehicles broke away from the main convoy and kept moving south, "continuing to pose a significant threat," NATO said. A second airstrike damaged or destroyed 10 of the vehicles.
"We later learned from open sources and Allied intelligence that Kadafi was in the convoy and that the strike likely contributed to his capture," the statement said.
The United Nations office for human rights has called for an investigation into how Kadafi died, since video footage taken after the airstrike appeared to show him bloodied but still alive.
-- Henry Chu
Photo: A Libyan fighter inspects the tunnels where Moammar Kadafi was claimed to have been found after NATO air strikes on his convoy. Photo: David Sperry / Associated Press