Two men accused of embezzling $1.8 billion from the Malaysian sovereign wealth fund 1MDB went on trial in Switzerland on Tuesday, the latest hearings stemming from the vast multibillion-dollar financial scandal.

Tarek Obaid and Patrick Mahony will plead not guilty, their lawyers have indicated.

They are accused by Swiss state prosecutors of involvement in a vast embezzlement operation orchestrated by Jho Low, an advisor to former Malaysian prime minister Najib Razak, with the complicity of the latter.

The 1MDB scandal has led to criminal investigations around the world, including in the United States, Switzerland and Singapore.

It is alleged that billions of dollars were pilfered from the fund, officially 1Malaysia Development Berhad, by a number of people and used to buy items ranging from artwork to a superyacht.

Former Malaysian premier Najib was sentenced in 2022 to 12 years in jail for offences linked to the misuse of public money in the 1MDB financial scandal. In February, his sentence was halved to six years.

The latest trial, which is due to last throughout April, is being held at the Federal Criminal Court of Switzerland in the southern city of Bellinzona.

Lawyers for one of the accused requested that the proceedings take place behind closed doors and the hearing was suspended, Switzerland's Keystone-ATS domestic news agency reported.

According to the original indictment, "the two accused are alleged, with the aim of enriching themselves and others, to have misappropriated at least $1.8 billion", transferred by 1MDB in connection with a joint venture with the Saudi oil exploration and production company PetroSaudi, "and then to have laundered the amounts involved".

"The allegations cover a period at least from 2009 to 2015 and constitute the offences of fraud on a commercial basis, aggravated criminal mismanagement, and aggravated money laundering."