The senate has suspended Ali Ndume, senator representing Borno south, for six months.
The upper legislative chamber took the action in line with the recommendation of its committee on ethics and privileges.
The committee had recommended the suspension of Ndume for “deliberately” bringing up an issue that painted the red chamber in a bad light.
It cleared Senate President Bukola Saraki of the allegation of taking vengeance on Hameed Ali, comptroller-general of the Nigeria Customs Service (NCS), for seizing a vehicle purportedly belonging to him.
It also cleared Dino Melaye, a senator from Kogi state, of the allegation of forging his degree certificate.
Last Tuesday, Ndume asked the senate to investigate the allegation that it was exacting vengeance on Ali because the agency had seized a vehicle of Saraki.
He also asked the senate to investigate the allegation against Melaye.
The committee presented the report of its investigation on Wednesday.
The upper legislative chamber and Ali have been locked in a battle of wits since the customs announced that it would commence collection of duty on old cars.
The service has since suspended the action.