"Two men were brought in yesterday (Friday) for questioning at the state's criminal investigation department," Bala Hassan, commissioner of police of Abia state, told AFP.

The pair, who are students at the state's university, were still being detained on Saturday but deny any role in the video.

Police were trying to identify the scene of the crime and the identity of those involved.

"We have gone back to the university to see if we can make more arrests based on information posted on the Internet," said Hassan.

"More than 15 detectives have gone to university hostels. They go around to check those names posted on the Internet and they are trying to identify the hostel seen on the Internet."

He said police had not received a complaint.

Investigators' initial response to the video has been criticised as lax.

"We are taking this seriously," Hassan insisted. "We want to find concrete information. Full names, not nicknames ... so that we can check on the registry of the university."

In a statement cited by local media, Abia's state government said it had run its own investigation and concluded that neither the alleged victim nor the perpetrators were linked to Abia's state university.

"The conduct of the Abia state government is inexcusable," said Chidi Odinkalu of the Open Society Justice Initiative help group, who added that most rapes in Nigeria go unreported.

"We've not provided a caring and thoughtful enough institutional framework to enable victims of rape to come forward," Odinkalu added.

Parliament had on Thursday called for a proper police investigation.

AFP