There was no immediate confirmation that NATO air strikes had taken place near the capital on Saturday evening, or that any Gaddafi aide had been wounded.
However, several explosions were heard in Tripoli itself throughout the afternoon, as late as 8 p.m. (1800 GMT), suggesting NATO was ramping up attacks after a quiet morning.
Spokesman Ahmed Bani said the aide, who he named as El-Khouwildy el-Ahmeildy, was a member of Gaddafi`s Council of the Leaders of the Revolution and that his daughter was married to one of Gaddafi`s sons.
Bani, who defected from Gaddafi, said the raid took place at about 1900 GMT on Saturday.
"El-Khouwildy el-Ahmeildy has been hit in a NATO air strike on a city close to Tripoli, and he is now being treated in a hospital," Bani told Reuters by phone from Benghazi.