The National Association of Nigerian Students has described the detention of Shehu Sani as unfair, prearranged and politically motivated.
The association said both the giver and the receiver in the alleged extortion should be investigated accordingly, and urged the EFCC to purge itself of criminal elements within its fold or as associates.
Meanwhile, the antigraft agency on Monday froze the bank accounts of a former senator.
In a statement, his senior special adviser also said the former lawmaker was forced to declare his assets.
EFCC had arrested Mr Sani for allegedly demanding money from Sani Dauda, the owner of ASD Motors, to bribe acting chairman of the agency, Ibrahim Magu.
This was to influence an investigation, an allegation the former lawmaker has denied. But the anti-graft agency insists he has questions to answer on the matter.