The US envoy to Canberra has raised concerns about China buying political influence in Australia, after a raft of revelations over Beijing's financial support for influential figures.

Political donations from foreign sources have become a highly sensitive issue in Australia, which last week saw the resignation of a leading opposition senator after he admitted taking payments to cover expenses.

"We have been surprised, quite frankly, at the extent of the involvement of the Chinese government in Australian politics," departing US ambassador John Berry said in The Australian newspaper on Wednesday.

"It is an entirely different matter when the government of China is able to directly funnel funds to political candidates to advance their national interests in your national campaign," Berry said.

"That, to us, is of concern. We cannot conceive of a case where a foreign donation from any government, friend or foe, would be considered legitimate in terms of that democracy."

Foreign donations are illegal in the United States, Australia's closest ally, and Berry urged Canberra to clean up.

"Our hope is that, in resolving this, Australia will consider doing what many other democracies have done: that is to protect their core responsibility against undue influence from governments that don't share our values."

The opposition Labor Party -- reeling from Senator Sam Dastyari's sudden downfall after a donor with links to the Chinese government paid for one of his expenses bills -- has proposed a ban on foreign donations in election campaigning.

Dastyari, a high-profile powerbroker, had also reportedly contradicted Labor and government policy on the South China Sea.

However Prime Minister Malcolm Turnbull's Liberal Party has also received large donations from Chinese firms and individuals, often with links to the Beijing government, and has shown little appetite for a ban.

"Look, Australia is a sovereign nation, but I can see no argument of how a foreign government's involvement through political contributions advances Australia's interests," the envoy said.

"In our country it's illegal. It would be against the law for any foreign donation to be accepted by any level of government or member of government."

China's rise and its sweeping claims to the South China Sea have seen a dramatic sharpening of Sino-US rivalry.

Australia has also become increasingly concerned about the purchase of domestic infrastructure and land by foreigners, and recently banned a sale by the country's biggest private landowner to a Chinese-led consortium.

However, the government's first foreign land register last week showed that British and US investors own far more agricultural land in Australia than Chinese nationals do.

Abe's Chinese calligraphy wins plaudits in China
Beijing (AFP) Sept 14, 2016 - Japanese Prime Minister Shinzo Abe earned unusual praise from Chinese netizens Wednesday -- but for the quality of his calligraphy, rather than his diplomacy.

Beijing and Tokyo are at loggerheads over disputed islands and wartime history, and Abe has raised hackles with his criticism of his neighbour's assertiveness in the South China Sea.

But the Japanese leader was lauded after he purportedly left a hand-written note in Chinese thanking a cleaner at the hotel he stayed in for the G20 summit in Hangzhou last week.

It gave Abe's name, title and the date, adding: "Thanks".

It was posted on China's Twitter-like Weibo last week by a journalist who founded what is said to be Japan's largest Chinese-language news website, and had been reposted more than 700 times by Wednesday.

"His characters are good-looking," wrote one poster.

Another appreciated his attention to detail, saying "This small gesture shows the nation's breeding", and adding the country was "formidable" and worthy of respect.

A spokesman at Abe's office could not confirm the authenticity of the note, but said that he had stayed at the Sheraton Grand hotel, on whose notepaper it was written.

The reaction is a contrast to how Abe is often portrayed by Chinese media and online, where an army of posters regularly comment in praise of Beijing's Communist government.

Abe has regularly been blasted by state-run Chinese media for his impenitent comments on Japan's wartime history and its invasion of China, publicly questioning claims that the Japanese military systematically compelled women to become sex workers.

In 2013 he visited Tokyo's controversial Yasukuni shrine, which honours the country's war dead including several high-level officials executed for war crimes after World War II.

The two countries are locked in a long-running dispute over uninhabited islets in the East China Sea, and Abe has vocally criticised China for rejecting a July ruling by an international tribunal invalidating its extensive claims to the South China Sea.

"Does he know that he is nearly scolded to death by Chinese people?" wrote one poster, adding "this behaviour can by no means draw any verbal abuse".