Former BSI banker Yeo Jiawei had accompanied Malaysian-born businessman Jho Low on his private jet for working trips, a Singaporean court was told.

According to the Straits Times, Yeo's former supervisor Kevin Swampillai revealed that Yeo even attended a boxing match in Las Vegas with Low last year, where the former banker snapped a selfie with ex-heavyweight champion Mike Tyson.

Swampillai, a Malaysian national, detailed the close working relationship between Yeo and Low, who is a central figure in the 1MDB imbroglio.

Testifying on the second day of the 1MDB-related trial, he said Yeo, 33, left BSI Bank in 2014 after Low expressed "interest in taking him on in some kind of capacity".

He added that Yeo, a Singaporean national, could have considered this as a better opportunity as Low was "constantly in the news, had quasi-celebrity status... and big investment deals around the world".

The prosecution had raised the close rapport between Yeo and the businessman as one of the reasons Yeo attempted to pervert the course of justice in the four charges he is now facing.

Seven other counts concerning cheating, money laundering and forgery are set for trial next year.

The former BSI wealth planner is accused of facilitating illicit transactions involving 1MDB that led to BSI's closure here.

Meanwhile, Swampillai also disclosed the measures taken to hide the US$5 million (S$6.9 million) in referral fees he received from "implementing various structures" and "undertaking financial arrangements" for BSI clients.

He said the idea of securing such commissions when the pair were on a trip to Labuan in 2012.

"We decided we would find an intermediary who would be used to identify certain funds, and have conversations with the funds about the nature of underlying transactions that would take place, and the kind of fees that the fund would earn.

"We were trying to find a margin between what the bank earned, what the fund managers earned, and create a margin that would be paid to Yeo and myself," he told the court.

Swampillai said Yeo and him received commissions from a number of entities, including Bridge Partners International Management, and a fund called Devonshire.

However, he added that the pair concealed these payments as BSI "clearly would not condone such a practice".

According to the US Department of Justice, Devonshire Capital Growth Fund was one of three funds used to divert US$1.59 billion of 1MDB Global Investment Limited's money to Tanore Finance.

The Straits Times report stated that Swampillai’s testimony also revealed the role of Yeo's associate, Samuel Goh Sze-Wei.

Yeo is alleged to have told the two men at a meeting at the Swiss Club in March to lie to the police about some fund transfers.

"Yeo kicked off the meeting saying, 'The time has come for us to hold hands together', and that we should align our stories. Given the fact that all three of us had been questioned by CAD (Singapore’s Commercial Affairs Department), the threat of exposure was very real," he said.

However, Swampillai said he decided not to go along with the plan when held for questioning since the "cover story had too many holes, and wouldn't stand up to any scrutiny".

Yeo's trial will run until Nov 11. Two other former BSI bankers Yak Yew Chee and Yvonne Seah have also been charged with money laundering.