SINGAPORE (Reuters) - Singapore's white-collar crime unit for the first time on Thursday identified Malaysian businessman Low Taek Jho as a key figure in the money laundering investigation linked to scandal-tainted 1MDB fund.

The revelation came from an investigator during the trial of a former wealth manager of Swiss private bank BSI in Singapore's most high-profile money laundering case. 

Low is also among the people named in civil lawsuits filed by the U.S. Department of Justice, which alleged that more than $3.5 billion was allegedly misappropriated from 1MDB.

Singapore authorities have also frozen Low's assets, however the 34-year-old has not been charged with any offense in the investigations into 1MDB.

Founded by Najib, who previously chaired its advisory board, 1Malaysia Development Berhad (1MDB) is currently the subject of money laundering investigations in at least six countries, including Switzerland, Singapore and the United States.

Najib has denied any wrongdoing and said Malaysia will cooperate with the international investigations.

Oh Yong Yang, an officer with the police Commercial Affairs Department (CAD), told a Singapore court Low had been under investigation since 2015.

"Low Taek Jho is a key person of interest in our investigation, and he is also a person of interest in related investigations in other jurisdictions... It started in 2015," he said.

He made the statement during the trial of Yeo Jiawei, a former wealth manager at Swiss private bank BSI who faces four charges related to his alleged attempt to pervert the course of justice by urging witnesses to lie to police and destroy evidence.

The CAD officer also said Eric Tan Kim Loong and Mohamed Ahmed Badawy Al Husseiny, former chief executive officer of Abu Dhabi's Aabar Investments, are also being investigated in the money laundering probe.

Husseiny was replaced as chief executive of Aabar last year after holding that post since 2010.

Yeo told the court Jho Low was a key client of BSI and also introduced 1MDB to the private bank.

Reuters could not reach Jho Low, Eric Tan or Husseiny for a comment.

Ex-BSI banker Yeo is also facing seven separate charges, including money laundering, cheating and forgery, which the prosecution said will be tried next year.

Singapore's central bank ordered the closure of the operations of BSI in May and asked the Attorney General's Chambers to investigate six members of BSI bank's senior management and staff.

Yeo's trial will last until Nov 11.

(Reporting by Fathin Ungku; Editing by Saeed Azhar)