The seven deputies and senators said they received virus-infected emails in 2021 sent by a hacker group called APT31, which several countries, including the US and Britain, believe to be linked to the Chinese government.

Their concerns emerged ahead of a state visit to France by Chinese President Xi Jinping, beginning with his arrival on Sunday, part of Beijing's efforts for deeper political and economic ties in Europe to counterbalance difficult relations with Washington.

"We are clearly faced with wide-ranging foreign interference by China," said Olivier Cadic, a centrist member of the French Senate.

The seven targeted parliamentarians all belong to the Inter-Parliamentary Alliance on China (IPAC), an international non-profit body for legislators who see China's policies as a threat to democratic values.

The French parliamentarians only discovered they had been hacked in March of this year after the US Justice Department indicted seven Chinese nationals "associated with the Chinese government" for sending malicious emails to US and foreign critics of China, including IPAC members.

Ex-senator Andre Gattolin, a former co-president of IPAC's French branch, said the US indictment was proof that a "Trojan Horse"-type email he received in 2021 came from the Chinese hacker group.

"At the time I was writing an extremely sensitive report about foreign interference in universities and research," he said.

But when he asked France's National Agency for the Security of Information Systems (ANSSI) to investigate further, "I couldn't get anybody's attention" there, nor at the anti-espionage agency DGSI, he told AFP.

He filed a police complaint last month, and IPAC got in touch with US law enforcement agency FBI which, he said, told them that they had informed the French authorities of their suspicions as early as 2022.

"But nobody told us anything," Gattolin said.

"I would like to understand why I wasn't alerted before," added deputy Anne Genetet.

The handling of the case by French authorities was "lightweight", she told AFP.

"It's unimaginable that I am the only National Assembly member this has happened to," she said.

The Paris prosecutors' office declined to comment on the case when contacted by AFP.

"I am concerned about how China's actions are met with complete silence," said Gattolin. "We may as well let Chinese spies walk right into our offices."

Asked in the Senate on Tuesday about the matter, government spokeswoman Prisca Thevenot said French services "are paying close attention" to APT31, "including under legality aspects".

But Cadic said such statements were insufficient. "We're dealing with an open official attack, and the authorities know it," he said. "What has been done to us is an act of war."