National deputy leader Paula Bennett says it was "extraordinary" for the State Services Commission boss to heap such praise on outgoing Treasury Secretary Gabriel Makhlouf while he is being investigated by the commission.

Last night, Makhlouf was farewelled at a function in the Beehive where Finance Minister Grant Robertson and State Services Commissioner Peter Hughes both paid tribute to Makhlouf's eight years of service.

Later this month, Makhlouf leaves the job to take over as the Governor of the Irish Central Bank.

The function comes as the State Services Commission (SSC) investigates the Budget leak and whether Makhlouf misled the