An Australian Senate committee has revealed that that country's mail chief is the nation's highest paid public servant and made A$5.6 million ($4.3 million) last year.

The Communications and Environment Committee announced on Tuesday that Ahmed Fahour, managing director of the national mail service, was paid A$4.4 million salary plus an A$1.2 million bonus in the last fiscal year - more than 10 times the prime minister's salary of A$507,000.

By contrast, US Postal Service Chief Executive and Postmaster General Megan Brennan's salary was $286,137 last year.

Australia Post had argued that revealing the salary package was not in the public interest. Australia Post and its top executives "may become targets of unwarranted media attention," the agency said in correspondence with the committee.

"This may lead to brand damage for Australia Post which when operating in a competitive market, may be significantly detrimental to our business and future profitability," Australian Post said.

Committee chairman James Paterson said on Wednesday that no senator on his committee agreed with Australia Post that the disclosure was contrary to the public interest.

Chief executives of publicly listed Australia companies are required to disclose their compensation at shareholder annual meetings and public sector executives should not be held to a lower standard of transparency, Paterson said.

"It's a matter for the Australia Post board and their remuneration committee and I trust them to make those decisions, but it's not appropriate to shield those decisions from public scrutiny," Paterson told Australian Broadcasting Corp.

Prime Minister Malcolm Turnbull, a former merchant banker with a personal fortune estimated at exceeding A$200 million, said he had told Australia Post Chairman John Stanhope "that remuneration is too high."

"As someone who spent most of his life in the business world before I came into politics, I think that is a very big salary for that job," Turnbull told reporters.

Australia Post made a profit of A$36 million in the last fiscal year that ended June 30, 2016. The previous year, it lost A$222 million due to the decline of traditional mail in Australia, a nation of 24 million people.

The highest paid Australian public servant after Fahour was Bill Morrow, chief executive of Australia's government-owned NBN Co, who was paid A$3.6 million last year, including an A$1.2 million bonus.

The company is rolling out Australia's national broadband network and is required to report its chief executive's compensation.