Foreign Minister Marise Payne says Yang Hengjun, an outspoken pro-democracy activist, is held under ‘harsh conditions’.

An Australian man of Chinese origin has been arrested in China after being accused of ‘espionage’, the foreign ministry in Canberra said in the latest of a series of detentions of foreign nationals visiting the mainland.

Australia’s Foreign Minister Marise Payne said in a statement on Tuesday that Yang Hengjun, an outspoken pro-democracy activist, has been held in Beijing in “harsh conditions”.

“We have serious concerns for Dr Yang’s welfare, and about the conditions under which he is being been held,” Payne added.

Yang, who was born in China, was jailed without charge in the southern city of Guangzhou in January amid growing tension between Australia and its largest trading partner.

Yang, who made a rare return to China from a trip to the United States, was formally arrested on Friday.

“If Dr Yang is being held for his political beliefs, he should be released,” Payne said.

“We expect that basic standards of justice and procedural fairness are met.”

According to reports, Yang had served in the Chinese foreign ministry before moving to Australia, where he worked as a writer and academic.

China’s refusal to grant consular access has been a point of friction in relations that have markedly deteriorated in recent months.

Beijing on Tuesday said Canberra should not “intervene” in China’s judicial processes.

“I would like to emphasise that China is a country ruled by law and the Australian side should earnestly respect China’s judicial sovereignty and must not intervene in any cases handled in China,” said foreign ministry spokesman Geng Shuang.

China’s growing clout in Pacific

There is a growing concern in Australia about Beijing’s influence on domestic politics and growing military clout in the Pacific.

On Monday, an official corruption inquiry heard that a well-connected Chinese property developer delivered an equivalent of about $67,000 in cash to the opposition Labour Party’s headquarters before a 2015 election.

The man, Huang Xiangmo, was effectively banned from returning to Australia in February.

Australia has traditionally been eager to avoid friction with its biggest trading partner, but Payne’s statement was unusually strongly worded.

“Dr Yang has been held in Beijing in harsh conditions without charge for more than seven months,” she said.

Payne said she had raised the case five times with her Chinese counterpart Wang Yi in person and via letters.

Yang had initially been held in “residential surveillance at a designated location” before being moved to “criminal detention”, his lawyer told AFP news agency.

On Saturday, the Chinese government released Simon Cheng, a 28-year-old Hong Kong resident and staff member of the British consulate, after several days of detention.

Cheng is a Hong Kong permanent resident and a holder of a British National Overseas (BNO) passport, a special document granted to people in the former British colony.

A BNO entitles holders to UK consular assistance but it does not equate to citizenship. The Chinese government does not recognise dual nationality for Chinese nationals.

In the case of Cheng, Beijing said that it is “entirely an internal affair”.