"The Libyan security services blew up the plane. They believed that opposition leader Mohammed al-Megrief was on board, but after the plane was blown up, it was found that he was not on the plane," said Shalgam, who defected from Moamer Kadhafi's embattled regime earlier this year.
On September 19, 1989, a UTA DC-10 travelling from Brazzaville to Paris via N'Djamena crashed in Niger after explosives on board detonated, killing 170 passengers and crew, including 54 French citizens.
A French court in 2009 sentenced six Libyan agents in absentia to life in prison for the attack, but Libya has never admitted it was responsible.
However, Tripoli had in 2004 agreed to pay $170 million in compensation to the families of the victims.
Shalgam also said that the 1988 bombing of a Pan Am flight over the Scottish town of Lockerbie that killed 270 people, for which Libya is widely believed to have been responsible, was more complicated than the UTA attack.
"The Lockerbie operation was more complex ... the role of states and organisations has been discussed, and while the Libyan services were implicated, I do not think it was a purely Libyan operation," he said.
Last February, a former official from the radical Palestinian group Abu Nidal said that the attacks against the Pan Am and UTA planes were conducted "in conjunction" with Libya, and that the explosives were fabricated in Libya.
Shalgam's defection came in March when he was was serving as Libya's representative to the United Nations.