Washington,  Chinese rights activists overseas have said that they are concerned but unsurprised at recent allegations that an agent of the Chinese Communist Party (CCP) was working at Twitter, saying such infiltration is part of Beijing's global influence operation, media reports said.

The FBI informed Twitter of at least one Chinese agent among its employees, according to US Senator Chuck Grassley, while hacker and whistleblower Peiter Zatko said the company's lax security sparked fears that personal data on Chinese users was being collected by authorities in China, RFA reported.

Zatko, Twitter's former head of security, levelled the allegations during his testimony before the Senate Judiciary Committee, detailing internal clashes between some who sought advertising revenue from China, and others who were concerned about doing business inside China amid rising geopolitical tensions, the report said.

"This was a big internal conundrum," Zatko told the hearing, adding that Twitter appeared reluctant to turn away from China.

"In a nutshell, if we were already in bed, it would be problematic if we lost that revenue stream," he said.

Zatko said the FBI had told the company that China's secret service, the Ministry of State Security, had an agent on the payroll, RFA reported.

A Twitter spokesperson said the microblogging platforms hiring process was independent of foreign influence, and that access to personal data was subject to stringent controls, adding that Zatko's allegations were "riddled with inconsistencies and inaccuracies."

France-based commentator Wang Longmeng said the CCP has long targeted Western social media platforms to wage its overseas influence campaigns, and that some of the company's regional executives have close ties to the CCP, including Kathy Chen, RFA reported.

Chen's 2016 appointment as Twitter's managing director for Greater China raised concerns in particular, as it emerged she had served as a software engineer in the People's Liberation Army's strategic missile force.

"Kathy Chen, who had a military background, joined [the company], then Fei-fei Li became an independent director," Wang said. "The CCP's infiltration of Western media is one of its key strategies."

"It's not surprising that the whistleblower revealed there are Chinese agents at Twitter, because there have been suspensions and deleted accounts, and yet Twitter still allows CCP diplomats to spread rumors and lies," he said, RFA reported.

While China bans Twitter, Facebook and other US social media firms, government agencies and diplomats use the platforms to reach an international audience.