SINGAPORE -- The Malaysian government stepped up pressure Tuesday on Goldman Sachs to pay back the $600 million in fees it earned from arranging three bond deals for state fund 1Malaysia Development Bhd in 2012 and 2013 as the investment bank comes under intense scrutiny in the U.S.

The scrutiny is due to former Goldman employees' role in arranging those three deals that raised a total of $6.5 billion for scandal-tainted 1MDB.

Malaysian Prime Minister Mahathir Mohamad said Goldman "cheated" Malaysia over the dealing with the state fund in an interview with CNBC aired on Tuesday. "There is evidence that Goldman Sachs has done things that are wrong," he said, adding that "obviously we have been cheated through the compliance by Goldman Sachs people."

Mahathir also said U.S. prosecutors had promised to help return 1MDB-related monies laundered that include Goldman. "It takes a little bit of time but they [Department of Justice] have promised to give back the money," he told reporters in Singapore.

Prime Minister-in-waiting Anwar Ibrahim went one step further to say the country should act in a more "aggressive" manner to seek damages from Goldman. "Now the U.S. [Justice Department] has commenced prosecution but Malaysia should act in a more aggressive manner to claim damages over our tarnished image," he said in a parliamentary debate Tuesday. "I believe the government has to take this step to seek returns far beyond the $600 million commission."

Goldman shares tumbled 7.5% on Monday in New York to end at $206.05, the lowest close since November 2016.

The sell-off started after Malaysian Finance Minister Lim Guan Eng said: "We would seek a full refund paid to Goldman Sachs." Lim told a Malaysian radio station BFM on Monday that on top of the fees, Kuala Lumpur will also try to recover other "consequential losses" including the higher yield for the $6.5 billion bonds Goldman underwrote for 1MDB.

A construction worker talks on the phone in front of a 1Malaysia Development Berhad billboard in Kuala Lumpur on Feb. 3, 2016.   © Reuters

The U.S. Department of Justice in early November indicted former Goldman partner Tim Leissner and former banker Roger Ng on three criminal counts, including bribery of overseas government officials.

According to the indictment, the two also conspired with Malaysian financier Jho Low, who was simultaneously indicted, to launder billions of dollars embezzled from 1MDB and paid bribes to various Malaysian and Abu Dhabi officials. Low's whereabouts is unclear.

According to the Justice Department, the payments to senior government officials were aimed at winning business, such as bond underwriting. In addition to the alleged bribes, the fund is accused of diverting cash to buy property in New York and artwork. More than $2.7 billion was misappropriated from 1MDB, the Justice Department said.

Goldman CEO David Solomon said he felt "horrible" about former employees' involvement in the 1MDB scandal. "It is obviously very distressing to see two former Goldman Sachs employees went so blatantly around our policies and so blatantly broke the law," he told Bloomberg Television on Nov. 7.

Minister Lim said Solomon's statement was "indirectly an admission that something very wrong happened."

Furthermore, The Wall Street Journal reported that former Goldman Sachs CEO Lloyd Blankfein met Low in 2009 and 2013. The report said the meetings were held to bring former Malaysian Prime Minister Najib Razak and Blankfein together. One of the meetings reportedly took place after Goldman's compliance department had expressed concerns about Low's background and recommended that the bank avoid any business dealings with him.

Justice Department officials said other Goldman Sachs employees, in addition to the two indicted bankers, knew about the alleged bribery, but did not reveal their names. The department is expected to move ahead with its probe into whether and to what extent Goldman as a company was aware that the dealings were illegal.

Since the global financial crisis in 2008, major U.S. financial institutions' business models have been called into question. If the former bankers are shown to have been involved in bribery and fraud, Goldman will draw more fire from its critics. Even if the bank itself is not shown to have been involved, it will have to come up with measures to prevent similar actions by its employees in the future.

1MDB is seen by many in Malaysia and elsewhere as a vehicle for corruption by the former Najib government. The fund was founded in 2009 and overseen by Najib. It invested in redevelopment projects in the capital, but allegations have surfaced that more than $4.5 billion was diverted from the fund into private hands, including Najib's.

After taking office in May, Mahathir has made uncovering corruption by the previous government a top priority. Malaysian officials have arrested and charged Najib and his wife, Rosmah Mansor, with money laundering and other crimes.

In late 2016, the Monetary Authority of Singapore issued a 10-year ban on Leissner engaging in securities transactions in the country.

Authorities in Malaysia, the U.S. and Singapore are jointly investigating this case.

Nikkei staff writers Takashi Nakano and Ryo Nakamura contributed to this story.