A Malaysian appeal court Wednesday upheld former leader Najib Razak's conviction and 12-year jail term over the multi-billion-dollar 1MDB scandal, which contributed to his government's downfall in 2018.

"We dismiss the appellant's appeal," judge Abdul Karim Abdul Jalil told the Court of Appeal in administrative capital Putrajaya.

"We affirm the High Court conviction on all seven charges."

The 68-year-old was found guilty on all counts last year in the first of several trials he is facing related to the looting of the 1Malaysia Development Berhad sovereign wealth fund.

Najib and his cronies were accused of stealing billions of dollars from the investment vehicle and spending it on everything from high-end real estate to pricey art.

The first trial related to the transfer of 42 million ringgit ($9.9 million) from a former 1MDB unit to Najib's bank accounts.

The ex-premier is now expected to lodge a last-ditch challenge at Malaysia's top court, and could remain free on bail until that appeal wraps up.