The US government is looking into claims that Syria restricted its citizens' access to the internet, using an American company's technology.
A group of hackers says it has downloaded data from the Syrian government telecommunications agency.
It says the records suggest equipment built by Blue Coat is being used to limit website access and, possibly, to monitor dissidents.
Blue Coat said it does not offer its equipment or services to Syria.
"We are actively investigating recent allegations that certain Blue Coat products have been sold or transferred into Syria and are being used by the Syrian government," the company said.
"Blue Coat does not sell its products into Syria, and prohibits its partners from selling Blue Coat products into Syria or other embargoed countries."
The United Nations estimates that around 3,000 people have been killed in Syria since a crackdown on anti-government protests began in March.
The Syrian authorities blame the unrest on "armed terrorist groups".
The US imposed sanctions against Syria in 2004, prohibiting the export of US goods with the exception of medicine and food.
However, the sanctions would not prevent Syria sourcing Blue Coat's surveillance hardware from a third party in another country.
"We are concerned about reports of the use of technology by repressive regimes in general, but Syria in particular, to target activists and dissidents," said Victoria Nuland, a spokeswoman for the US State Department.
"We are reviewing the information that we have and monitoring the facts."
Syria's alleged use of the equipment might be limited because the US firm would not provide it with support services.
However, Blue Coat does not have a remote "kill switch" to stop its kit from working, because the facility would leave its products vulnerable to external attacks.
The allegations against Blue Coat originate with Telecomix, a group founded by Swedish hackers which describes itself as a "telecommunist cluster".
It said it downloaded 54 gigabytes of Syrian telecoms data in August.
The group says the files contained evidence of "web filtering and monitoring", and when it scanned internet protocol addresses associated with the Syrian authorities, some of them responded as being Blue Coat devices.
One member of Telecomix, who is known by the nickname KheOps, told the BBC: "Also, we have info from the ground to confirm the info."
Another member, known as okhin, said it was likely that Syria had not bought the devices directly from Blue Coat because "those devices are extremely poorly configured, and we think that when Blue Coat sells devices they usually sell technical skill to configure and use them".
Blue Coat announced earlier this month that 85% of the Fortune Global 500 companies use its products. It also offers families free web filtering software to block pornography and gambling pages.
However, the London based campaign group, Privacy International, said it wants Blue Coat, and its competitors, to face further scrutiny.
"Companies that manufacture surveillance technologies that facilitate the scope and levels of intrusion that Blue Coat's does must be aware of the potential havoc their products can wreak," said the group's human rights and technology adviser, Eric King.