* Facebook, Google among companies affected by new law
* Law essential to fight cyber crime, authorities say
* Critics warn of potential harm to investment, free speech
By Mai Nguyen
HANOI, June 12 (Reuters) - Vietnamese lawmakers approved a controversial cybersecurity law on Tuesday, voting amid tight security following weekend protests over other legislation that turned violent in some parts of the communist country.
The law, approved by 91 percent of attending lawmakers, would require Facebook, Google and other global technology firms to store locally "important" personal data on users in Vietnam and open offices in the country. The companies have pushed back against the provisions.
The vote took place two days after thousands of demonstrators took to the streets in several cities and provinces to denounce a plan to create new economic zones for foreign investment that has fuelled anti-Chinese sentiment in the country.
Security was tight ahead of Tuesday's vote, with police manning barricades outside the National Assembly in the capital Hanoi.
Some protesters on Sunday had derided the cybersecurity bill, which experts and activists say could cause economic harm and stifle online dissent.
The United States and Canada had urged Vietnam to delay the vote and review the cyber law to ensure it aligned with international standards amid worries it may present serious obstacles to Vietnam's cybersecurity and digital innovation future.
Canada said some of the localisation requirements might increase costs, uncertainty and risks for Canadian businesses and inhibit their global operations.
The Vietnam Digital Communication Association (VCDA) said the requirements could reduce Vietnam's gross domestic product by 1.7 percent and wipe off 3.1 percent of foreign investment. Trade and foreign investment are key to Vietnam's economy.
It also raised fears about tougher restrictions on online dissent by requiring social media companies in Vietnam to remove offending content from their platforms within one day of receiving a request from the authorities.
Human Rights Watch said last week the bill targets free expression and access to information, while Amnesty International said the law would allow Vietnamese authorities to force tech firms to hand over data to censor users' posts.
Vo Trong Viet, head of the defence and security committee which drafted the law, said the requirement to store data inside Vietnam was feasible, crucial to fighting cyber crime and in line with international rules.
"Placing data centre in Vietnam increases costs for businesses but is a necessary requirement to meet the cybersecurity need of the country," he told lawmakers. (Reporting by Mai Nguyen Editing by Martin Petty and Darren Schuettler)