The Special Affairs Department (Jasa) insisted that ex-BSI banker Yeo Jiawei's conviction in Singapore does not implicate 1MDB president Arul Kanda Kandasamy and Prime Minister Najib Abdul Razak in the 1MDB investigations.

"Many have asked why Yeo was sentenced to 30 years (sic) by the Singaporean court recently.

"The answer (is) Yeo was convicted on witness-tampering charges, in the money-laundering case which was investigated by the Singaporean Commercial Affairs Department (CAD)," Jasa said in a statement today.

Yeo was handed a 30-month jail sentence for tampering with witnesses involved in Singapore's investigations into 1MDB.

He was accused of tampering with witnesses who were crucial to Singapore's investigation into money-laundering charges related to 1MDB.

The court heard that Yeo had met with ex-income distribution chief Samuel Goh Sze-Wei and and his former supervisor at BSI Kevin Swampillai and asked them to lie to the authorities about several fund transfers.

He had also asked them to conceal the true story, until the authorities revealed evidence that proved otherwise.

He also asked Amicorp relationship manager Jose Renalto Carvalho Pinto to avoid coming to Singapore so he would not questioned by the CAD, as well as asking Pinto to get rid of his laptop with evidence of illicit business transactions.

Pinto was also asked by Yeo to tell another Amicorp Group employee Aloysius Mun to pretend to the CAD to have no knowledge of Yeo's business dealings.

Jasa said the facts of this case showed that Yeo's convictions had nothing to do with Arul Kanda or Najib.

"Was 1MDB the one which was being investigated and heard in court?

"Based on the facts of this case so far, the investigations and court proceedings is not about 1MDB but more about the investigation on BSI Bank in Singapore and the funds under BSI Bank," it said.

Yeo faces several other charges - from forgery to money-laundering - related to his dealings with Malaysian businessman Jho Low.

The trials for the other charges will begin in April next year.

The court previously heard that Yeo had worked with Swampillai and intermediaries to make "secret profits".

Among their source of secret commission was Bridge Partners International Management, where 1MDB's "fund units" were held, Swampillai testified.

Another source of commission, Swampillai said, was a fund called Devonshire.

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.

It was also revealed in court that Yeo left BSI Bank in 2014 to work for Low and that he received information about Malaysia's top officials directly from Low.

Yeo was privy to such information because he was with the team that structured the 1MDB and SRC International investments, which were by then under heavy scrutiny, Pinto testified in court.

Yeo's 30-month jail sentence makes him the third BSI banker to be jailed under Singapore's investigations into the 1MDB money trail.

Yak Yew Chee is now serving an 18-week jail term on forgery charges and failure to disclose suspicious transactions.

Yak's subordinate Yvonne Seah had also pleaded guilty to similar charges and was handed a two-week jail sentence.