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

Najib now plans a final appeal to Malaysia's top court and will remain free on bail until that challenge concludes.

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.

His first trial related to the transfer of 42 million ringgit ($9.9 million) from a former 1MDB unit to his bank accounts.

He challenged last year's High Court ruling at the Court of Appeal, but judge Abdul Karim Abdul Jalil Wednesday upheld Najib's conviction on all seven charges he faced.

The judge condemned Najib's actions as a "national embarrassment", and said he had "knowledge of the 42 million ringgit (sent) into his account and dishonestly misappropriated it".

Najib was convicted of abuse of power, money-laundering and criminal breach of trust over the transfer. As well as the jail term, he was fined almost $50 million. 

Judge Karim also rejected Najib's defence that he believed the money was a donation from Saudi royalty, saying there was "no evidence" for the claim.

He agreed to a request for Najib to remain free on bail while he lodges his last appeal.

Najib and his lawyers were not at the court in administrative capital Putrajaya for the ruling and followed the proceedings online, after a member of the legal team tested positive for Covid-19. 

- Final challenge -
Anger at the plunder played a large part in the shock loss of Najib's long-ruling coalition at elections in 2018, and he was arrested and hit with dozens of charges following his defeat. He has consistently denied any wrongdoing.

His lawyers had sought to delay Wednesday's ruling over the Covid case in Najib's legal team, and by seeking to introduce new evidence at the 11th hour as part of the appeal. But the court rejected both moves. 

The former prime minister's final appeal to Malaysia's top court will likely take months.

If Najib -- who remains an MP -- loses that challenge, he will be jailed and barred from holding political office. 

Despite his graft conviction, he remains popular and influential, and has been mounting a political comeback in recent months.

The blue-blooded politician, whose father and uncle were both prime ministers, projects himself as a man of the people and has 4.6 million followers on Facebook, where he frequently comments on the news and criticises rivals.

He campaigned at local polls last month in the bellwether state of Malacca, helping his party, the United Malays National Organisation (UMNO), to a landslide victory.

The amounts involved in Najib's first case are small compared with those in his second and most significant 1MDB-linked trial, which centres on allegations he illicitly obtained more than $500 million.