A former Facebook adviser is urging governments concerned about the impact social media is having on democracy to shut down the platforms until they are reformed.

Speaking to the House of Commons privacy and ethics committee Tuesday, Roger McNamee, a venture capitalist who mentored Facebook founder Mark Zuckerberg, said the time has come to 鈥渃all their bluffs鈥� and force social media giants to make changes to their business practices.

鈥淚f your goals are to protect democracy and personal liberty, you have to be bold. You have to force a radical transformation of the business models of internet platforms鈥� McNamee said.

鈥淎t the end of the day, the most effective path to reform would be to shut the platforms down at least temporarily鈥� any country can go first.鈥�

McNamee was one of many experts on hand to testify at the international grand committee on big data, privacy and democracy meeting in Ottawa, examining the role of internet companies in safeguarding privacy and democracy rights.

While Canadian MPs, international politicians, and representatives from some of the world鈥檚 biggest tech companies were present, Facebook鈥檚 chairman and CEO Zuckerberg and chief operating officer Sheryl Sandberg, both of whom were subpoenaed to appear, were noticeably absent.

In his testimony, McNamee backed up his suggestion by pointing to the Sri Lankan government鈥檚 decision to ban social media sites in the wake last month鈥檚 deadly Easter Sunday bombings to prevent the spread of disinformation.

McNamee, who wrote , said 鈥渁t a minimum鈥� governments should ban social media sites from tracking and collecting users鈥� personal data and invasive surveillance practices.

He also suggested taxing micro-targeted advertising to make it 鈥渆conomically unattractive鈥� to businesses like Facebook or Google.

鈥淭he people at Facebook and Google are not evil,鈥� he said. 鈥淭hey are products of an American business culture with few rules, where misbehaviour seldom results in punishment.鈥�

During the meeting in Ottawa, the committee will hear from experts about how governments can prevent the use of social media to violateprivacy, spread so-called fake news and manipulate election outcomes.

Before the meeting, Facebook, Google and Microsoft signed a declaration promising a dozen initiatives to protect the integrity of the Canadian election this fall, which includes the removal of fake accounts and content.

Zuckerberg and Sandberg鈥檚 failure to attend the meeting could result in the executives being held in contempt of parliament. However, it鈥檚 not clear what consequences that might have.