It is learnt that exco member Lim Hock Seng is currently being questioned, with Deputy Chief Minister II P Ramasamy to be called in tomorrow.
Lim is Penang Public Works Committee chairman while Ramasamy heads the economic planning portfolio.
MACC has recorded 76 witness statements on the matter to date.
The last major arrest involved the chief executive and an engineer of a consultancy firm, who are alleged to have falsified claims in the feasibility studies and detailed design of the project.
Five people have been arrested and released on remand.
The 7.2km undersea tunnel will connect George Town’s Pangkor Road and Bagan Ajam in Butterworth. Construction is scheduled to begin in 2023.
The tunnel’s feasibility study, a topic of contention between government and opposition leaders, was at 95.9% as of last December.
The Penang government has said the tunnel is of low priority and can take off later, after the three main highways are completed.
The “three main roads”, formerly called the three paired roads, stretch from Air Itam to the Tun Dr Lim Chong Eu Expressway (5.7km); Tanjung Bungah to Teluk Bahang (10.53km); and Jalan Pangkor-Gurney Drive junction to Tun Dr Lim Chong Eu Expressway (4.1km).
FMT has contacted MACC deputy chief commissioner (operations) Azam Baki and is awaiting his response.