Sydney: China has denied entry to a Chinese-born Australian who was travelling to Shanghai with his mother to return his father's ashes to the land of his birth, he said on Wednesday.

John Hugh, 51, who has been an outspoken critic of the Chinese Communist Party's efforts to influence Australian politics, said he was sent back to Sydney soon after his flight landed in Shanghai on Tuesday night.

He said he was met by Chinese officials before disembarking and told that he would be put on the next flight back to Australia.

"I asked what the reason was, and they just said, 'You should know,'" he said.

Hugh, a former city council member from Parramatta in western Sydney, surmised that he had been refused entry as punishment for his support for a new espionage bill intended to regulate foreign influence in Australia, and for his connection to a new book about the Chinese Communist Party's efforts to infiltrate Australian politics, business and academia.

In Clive Hamilton's book, Silent Invasion, Hugh is quoted criticising the party's efforts to limit dissent, not just in China but in Australia.