The accused are likely to be indicted in the next hearing, Dawn News reported.
The accountability court was hearing the Oil Gas and Power Regulation Authority (OGRA) corruption case during which former OGRA chairman Tauqir Sadiq and another main accused Dewan Ziaur Rehman appeared in the court.
Rehman is accused of corruption amounting to 52 billion rupees.
NAB has been investigating 12 rental power projects cases in which nine firms reportedly received more than Rs 22 billion as mobilisation advance from the government to commission the projects, but most of them were accused of failing to set up plants.
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Ashraf, a former federal minister for water and power, was the head of the selection committee which had approved it in OGRA references.
Gilani was charged by the NAB with illegally appointing former OGRA chairman Sadiq in 2009.
However, Gilani says that since he took this decision as prime minister, it could not be challenged while he was in office.
Ashraf and former finance minister Shaukat Tareen appeared for today's hearing in the court.