The restrictions, which the sources said were carried out by state-owned telecommunications companies, knocked the servers offline for around seven weeks, meaning the website became unusable at times.
“We believe the action was taken to place significant pressure on us to increase our compliance with legal takedown orders when it comes to content that our users in Vietnam see,” the first of the two Facebook sources told Reuters.
In an emailed statement, Facebook confirmed it had reluctantly complied with the government’s request to “restrict access to content which it has deemed to be illegal”.
Vietnam’s foreign ministry, which handles requests from foreign journalists for comment from the government, did not respond to a Reuters request. State telecoms firms Viettel and Vietnam Posts and Telecommunications Group (VNPT) also did not respond to requests for comment.
Facebook has faced pressure to take down anti-government content in many countries over the years.