Penang Deputy Chief Minister II P Ramasamy was quizzed for six hours by the Malaysian Anti-Corruption Commission (MACC) over his role and involvement in Penang's RM6.3 billion undersea tunnel project.

Ramasamy was present at the MACC office in Penang at 9 am today and was released at 4 pm.

Accompanying him to the MACC were his lawyer Ajit Singh and law lecturer Shamsher Singh Thind.

Like state executive councillor Lim Hock Seng who was grilled for 12 hours yesterday, Ramasamy was questioned as a witness, not a suspect, as part of MACC's major probe into the project. The probe began early this year.

Ramasamy said two MACC officers took down his personal details and later interviewed him on his knowledge of the proposed 7.2km tunnel project to link the island to Butterworth on the mainland.

"I am out in one piece," he quipped when contacted upon his release from the state MACC office late afternoon.

"Most of the time was spent verifying documents, including minutes of meetings on the tunnel project," Ramasamy told Malaysiakini.

"I was also asked about my relationship with the project's two high-ranking officials with “Datuk” titles who were nabbed by MACC last month to help with the probe," he added.

"I only know them insofar as we meet at official meetings and functions," Ramasamy stressed.

He said he had no issues with the MACC officers who queried him as they were "polite and merely carrying out their duties".

The graft watchdog has queried more than 70 individuals and nabbed four high-ranking corporate figures involved in the tunnel project to assist in the probe.

The commission is looking into the possibility that millions of ringgit in kickbacks were given to politicians allegedly involved in the project.

The MACC investigation and its motive have been questioned by Chief Minister Lim Guan Eng, who said the project, which is slated to begin construction in 2023 for completion in 2027, was awarded to Consortium Zenith Construction Sdn Bhd in 2013.

BN leaders have criticised Lim over the project, questioning the state's competency, accountability and transparency in handling the matter.

Lim has shot back, saying all the project's transactions were above board and slammed BN for attempting to sabotage the project which he said was vital to address the state's traffic woes.