Pressure is mounting on Malaysian Prime Minister Najib Razak to explain his family's outsized wealth, with former premier Mahathir Mohamad joining the chorus of critics.
Dr Mahathir said people wanted to know where Mr Najib's stepson, Riza Aziz, obtained the funds used to produce a Hollywood movie as well as invest in real estate worth tens of millions of dollars in the United States.
Spokesmen for Mr Najib, himself the son of a former prime minister, have said that his family has a sizable sum from an inheritance, but they did not address the source of Mr Riza's wealth directly.
However, even the prime minister's own brothers have denied that the inheritance was large enough to support activities on the scale reported.
Riza Aziz burst onto the Hollywood scene two years ago as a co-producer of the Oscar-nominated movie Wolf of Wall Street, starring Leonardo DiCaprio. He is also a co-producer of the comedy Dumb and Dumber To.
"The movie did not rake in any profits. It is impossible that the money made from the movie was used to purchase luxury properties worth millions of US dollars," Dr Mahathir wrote in a blog posting, The Malaysian Insider reported.
"The question is, if the money had not come from [Najib's] family, then where did such a large amount come from? Is it from a business? If yes, what business, where? Has the income tax been paid? To which government?"
Film producer Riza Aziz (left), the stepson of Malaysian Prime Minister Najib Razak, arrives for a movie premiere in London in October last year with British actor Daniel Radcliffe, British actress Juno Temple and producer Joey McFarland, a business partner of Mr Riza. (AFP Photo)
Mr Riza has also raised eyebrows with a series of property purchases far out of proportion with his earnings from a previous job as a junior banker in London.
A recent New York Times investigation into the US real estate holdings of foreign tycoons featured businessman Low Taek Jho, whose transactions involved various parties, including Mr Riza.
The article also detailed the jet-set lifestyle of Mr Low, who was shown partying with socialite Paris Hilton.
According to the Times, in 2010 a shell company linked to Mr Low purchased a $24-million condominium in the Park Laurel building in Manhattan. Three years later he sold it to Mr Riza. Mr Low also purchased a $17.5-million mansion in Beverly Hills, California and sold it later to the prime minister's stepson.
Mr Loh denied the claims but the Times said its investigation traced the network of shell companies used for the transactions back to him.
A third purchase involved a $30.5-million unit, once owned by the pop superstar Beyonce, in the Warner Center condominium. Mr Loh told the Times he had not purchased the condo for investors but that it was owned by a family trust.
Mr Low has also been linked to the controversial state investment vehicle 1Malaysia Development Berhad (1MDB), which has chalked up debts of 42 billion ringgit (372 billion baht or $11.3 billion).
Concern about 1MDB has taken a big toll on investor confidence in Malaysia in recent months and contributed to a slide in the rupiah, Asia's worst-performing currency this year.
The Times also revealed the "incredible wealth" of Mr Najib’s immediate family members and raised questions how the wealth was accumulated.
Mr Najib, who earns about $100,000 a year as prime minister, has been dogged by reports of the extravagant spending habits of his second wife Datin Seri Rosmah Mansor, the mother of Mr Riza. Her collection of jewellery and nine Hermes Birkin handbags, which cost anywhere from $9,000 to $150,000 each, is a subject of endless gossip among Malaysians.
The Times also said it had seen invoices for "millions of dollars" worth of jewellery purchases made by Ms Rosmah in Hong Kong in 2008 and 2009.
Mr Riza told the Times that he was personally wealthy but declined to discuss the source of his funds.
The Prime Minister's Office told the newspaper: "The prime minister does not track how much Mr Riza earns or how such earnings are reinvested."
As for the accounts of family spending, including a claim by an opposition member that Mr Najib kept "piles and piles" of cash in a safe, the PM's Office said: " ... neither any money spent on travel, nor any jewellery purchases, nor the alleged contents of any safes are unusual for a person of the prime minister’s position, responsibilities and legacy family assets".
Instead, it said Mr Najib's wealth came from a family inheritance.
However, Mr Najib's four brothers have since issued a statement dismissing talk of the extent of the inheritance left by their father, the late Tun Abdul Razak Hussein.
Mr Najib later joined his brothers and described their father as frugal and a man of integrity.
Opposition leaders have urged the premier to address questions raised about his accumulated wealth.
On Thursday, PAS Youth, a wing of the opposition Pan-Malaysian Islamic Party, lodged a report to press authorities to investigate reports of Mr Najib living a life of luxury.