An ad hoc committee of the House of Representatives has summoned heads of four government agencies to appear before it on August 19.
This followed the ruling of the chairman of the committee, Yusuf Buba, at a public hearing on Thursday in Abuja.
The agencies ordered to appear are the Nigerian Custom Service (NCS) Nigerian National Petroleum Corporation (NNPC) Central Bank of Nigeria (CBN) and State Security Service (DSS).
The chairman said the committee resolved to take the action as the chief executives failed to honour the invitation to appear before it for an investigative public hearing.
The public hearing was on the need to determine why the Warri, Port Harcourt, Calabar, Onne and Onitsha inland complexes are not being put into maximum use.
Buba said it was an important matter and the committee would not let any individual or group treat it with levity.
He said the lawmakers were determined to get to the root of the matter and ensure the ports operated to full capacity.