Broad US sanctions aimed at keeping certain technologies out of the hands of repressive regimes can often backfire by hurting democracy movements, a think tank report said Thursday.

The New America Foundation study said US sanctions policies "remain largely outdated in recognizing how communications technology can benefit both the civilian population and serve broader American foreign policy goals."

It added that the broad-brush sanctions "often have negative consequences on the populations in sanctioned countries, inadvertently aiding the repressive regimes that seek to control access to information within their borders."

The researchers urged a move to "smart sanctions" which could deny targeted governments the ability to monitor and silence opposition movements, while allowing more access to personal communications tools.

"These technologies increase citizens' ability to access and share information and communicate with each other," said Danielle Kehl, one of the authors of the report.

"They can also provide stronger protection against censorship and surveillance from local governments than the alternatives people rely on if American products are blocked by sanctions."

The report examined sanctions on Iran, Syria, Sudan, Suba and North Korea, where US companies are barred from selling many types of telecommunications equipment.

Because of this, researchers told a forum discussing the report, citizens in those countries often use outdated software that is riddled with security holes which can be easily exploited by the regimes.

"If you are in Iran you cannot get a legitimate copy of your operating system," said Collin Anderson, an independent researcher who contributed to the report.

He said because the software is often illegitimate, it cannot get security updates and governments "are going to (insert) malware (on) everybody ... State-sponsored actors use this as a way to round up political dissidents."

Ian Schuler, a former State Department official who now heads a digital activism group, said that in the United States "there is general agreement that the free flow of ideas is beneficial to everyone."

But Schuler told the forum that refining sanctions policies is complex because some technologies "can be used for good things or for bad things."

The report said exemptions should be made in sanctions for "personal communications tools, from email to anti-filtering software," saying they "clearly enhance the free flow of information, enabling citizens in repressive countries to communicate with one another and with the outside world."