An Australian writer feared detained by Chinese authorities has told his family he is okay.
Spy novelist and influential online commentator Yang Hengjun disappeared on Sunday shortly after calling a colleague from a Chinese airport to say he was being followed.
Friends fear Dr Yang has been detained by Chinese authorities as part of their crackdown on political expression in the wake of the democratic uprisings sweeping the Middle East and north Africa.
Li Huizhi is a Chinese blogger living in the southern city of Guangzhou, and a close friend of Dr Yang.
He told the ABC the conversation he had with him last night left him extremely worried.
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"Our conversation involved only four sentences," Mr Li said.
"'I'm sick.' This was the first sentence. 'It's a misunderstanding.' That was the second. 'Did you write about me on your blog?' the third. And finally 'I'll explain all this in a few days'," mr Li told the ABC.
"I am highly suspicious of whether or not he's sick," Li Huizhi said.
"We're very close friends. If he's really sick he'd explain this to me clearly and he'd ask me to go over there.
"But this time he only spoke four sentences and then hung up. It's never happened before."
The Department of Foreign Affairs and Trade says Dr Yang's circumstances remain unclear.
"We are aware Dr Yang spoke to his family on 30 March, 2011 to say he was well," a DFAT spokesperson said. "We are seeking urgently to speak to him directly to confirm his situation."
China's Foreign Ministry has publicly said it has no information on Dr Yang. Foreign Minister Kevin Rudd is yet to comment on the case.
But government backbencher Michael Danby says Dr Yang's apparent detention was "unacceptable".
"He should be released," Mr Danby told ABC television.
"We're getting a bit sick and tired in this country of Australian citizens being arrested by the Chinese state.
"It's very contemptuous and it's actually provocative before the prime minister arrives there."
Prime Minister Julia Gillard is expected to visit China in late April. The federal opposition says Dr Yang's circumstances are "deeply troubling".
"We have called on the Chinese government to contact Australian officials and work with them to explain his whereabouts," coalition foreign affairs spokeswoman Julie Bishop said.
Amnesty International said Dr Yang's disappearance was extremely worrying.
"He joins a long list of peaceful reformists who have gone missing or been arrested in China in the last month," Asia Pacific deputy director Catherine Baber said.
"There is no sign of this crackdown easing."
Dr Yang's novel Fatal Weakness deals with espionage between China and the United States.
His political writings have dealt with government corruption and calls for democracy.
