SYDNEY — Australian Prime Minister Malcolm Turnbull was on Thursday accused of "buying" his narrow election victory last year after he admitted personally gifting A$1.75 million (US$1.32 million) to the cash-strapped Liberal Party campaign.

The multi-millionaire former banker, known as "Mr Harbourside Mansion", had repeatedly dodged questions about the issue, but changed his mind during an interview with the Australian Broadcasting Corporation.

"I contributed A$1.75 million, that was the contribution I made," Turnbull said late on Wednesday.

"It’s been talked about and speculated about, so there it is."

The Sydney Morning Herald said it was the largest political donation by an individual in Australian history.

Turnbull’s Liberal/National coalition was narrowly re-elected after a fiercely fought campaign last July, and the Labor opposition claimed it effectively bought power.

"It stinks. Malcolm Turnbull had to buy his way out of trouble," said shadow finance minister Jim Chalmers.

"He couldn’t win an election on his merits so he got out his wallet.

"If he didn’t have $1.75 million to splash about he wouldn’t be the leader of the Liberal Party and he wouldn’t be the prime minister."

Reports said the cash was used to fund television advertising, direct mail-outs and opinion polls.

Treasurer Scott Morrison lashed out at Labor’s "grubby smear" of Turnbull.

"It’s a grubby political smear from a grubby political hack, from a party of hacks led by Bill Shorten," he said.

Turnbull is reportedly worth A$200 million through his previous careers as a barrister, businessman and investment banker.

Under Australian law, political parties receive public funding according to how well they perform in an election.

The funding, which is received after the polls, is usually insufficient to pay for campaigns, with parties having to approach donors -- individuals and companies -- to boost their kitty.

Labor relies on donations and affiliation fees from trade unions for much of its funding.

All donations above A$13,000 at the national level have to be disclosed.

Turnbull’s gift did not show up in Australian Electoral Commission figures released this week for the last financial year ending on June 30, piling pressure on him to come clean.

It turned out the donation was made in the current financial year - pledged before the election but the cash arriving after the polls -- and so could have remained secret for another 12 months. — AFP