According to a new report from Reporters Without Borders, no one does online censorship like Iran, Syria, and China.

The Paris-based media watchdog Reporters Without Borders (RSF) says China, Iran, Syria, Bahrain, and Vietnam are the world's worst offenders in terms of Internet censorship and spying.

RSF said in a new report that regimes clamping down on dissent should not have easy access to Internet surveillance tools.

The report, "Enemies of the Internet," also singled out five companies that it said are "digital-era mercenaries" who help oppressive regimes.

The report said China "runs one of the world's biggest digital empires" due to the so-called Great Firewall of China, which can filter foreign websites.

Iran is mentioned for creating an isolated Internet system, which Tehran says it needs to stop foreign cyberattacks on nuclear installations.

Russia is criticized for blacklisting "harmful" websites in the name of "protecting minors."