Nigeria’s upper chamber of parliament voted on Tuesday to halt a concession agreement with the local division of Italian oil company Eni to repair, operate and maintain Port Harcourt refinery, saying the deal lacked transparency, Reuters reports.

Members of the Senate voted to back the motion brought by Senator Sabo Mohammed. The motion was titled: “Non-transparent transaction relating to the planned concession of the Port Harcourt refinery to Agip and Oando by the Ministry of Petroleum Resources.” Agip is a subsidiary of Eni.

The Senate will now set up an ad hoc committee to investigate the concession award. Eni said in May it was in talks to work with Nigerian energy company Oando on the deal as part of an effort to increase refining levels. While Eni could not be reached, Oando spokesman Ainoije Irune said; “We are willing and available to provide as much clarification on the issue as the Senate requires.”