SELDOM have Australia’s complex relations with China been more starkly exposed than in the agonies of Sam Dastyari, a prominent opposition MP. Three months ago Mr Dastyari gave a press conference with Huang Xiangmo, the head of Yuhu Group, a subsidiary of a property company linked to China’s government. Contradicting both the government’s line and the policy of his own party (Labor), Mr Dastyari called on Australia to “respect” China’s ill-founded territorial claims in the South China Sea, according to reports in the Chinese press.

Mr Dastyari, it recently emerged, has accepted donations from Yuhu and from the Top Education Institute, a local firm run by a Chinese-Australian with close ties to the governments of both countries. Mr Dastyari used the money to pay for travel and legal advice. Yuhu also gave Mr Dastyari two bottles of Penfolds Grange, Australia’s most expensive wine, worth around A$800 ($600) a bottle. From the G20 summit in China, Malcolm Turnbull, Australia’s prime minister, described Mr Dastyari’s behaviour as “cash for comment”.

On September 7th Mr Dastyari resigned from a post within the Labor party, but not as an MP. Although he admits that accepting the money was “a big mistake”, he denies any link between the donations and his remarks on the South China Sea. The donations, he points out, had been declared as required and were perfectly legal. Australia’s politicians and political parties, it transpires, took A$5.5m in donations from Chinese-linked firms in the two years through June 2015, including A$500,000 from Yuhu. Many are now calling for donations from foreigners to be banned.

China is Australia’s biggest trading partner, and one of its biggest sources of immigrants. Chinese demand for Australian resources, as well as ever-increasing numbers of Chinese tourists and students, have helped to underpin Australia’s 25 years of unbroken economic growth. But many Australians worry that the pursuit of Chinese business is undermining their country’s independence.

Mr Turnbull seems to agree. In April his government vetoed a bid by Dakang, a Chinese company, for S. Kidman and Co, a vast outback empire of cattle ranches that owns 2.5% of Australia’s agricultural land. Last month it turned down bids by State Grid, a Chinese government-owned company, and Cheung Kong, of Hong Kong, for a 50.4% stake in Ausgrid, an electricity-distribution network in New South Wales, Australia’s most populous state.

Scott Morrison, the treasurer (the most senior finance minister), said both bids were “contrary to the national interest”, without explaining how. Yet British firms own 7% of Australia’s agricultural land, without apparently damaging the national interest. And State Grid already owns stakes in several electricity distributors in other parts of Australia. The rules have not changed since those investments were made but, judging by the uproar about Mr Dastyari, the mood has.

Correction: An earlier version of this story said the Australian government turned down a joint bid by State Grid and Cheung Kong for a stake in Ausgrid. In fact, the two companies made separate bids.