LONDON - The maker of one of the Internet's most popular browsers is taking on one of the world's best-known purveyors of surveillance software, accusing a British company of hijacking the Mozilla brand to camouflage its espionage products.

The Mozilla Foundation — responsible for the Firefox browser — said late Tuesday that Gamma International Ltd. was passing off its FinFisher spy software as a Firefox product to avoid detection. Mozilla described the tactic as abusive.

"We are sending Gamma, the FinFisher parent company, a cease and desist letter demanding that these practices be stopped immediately," Mozilla executive Alex Fowler said in a statement from the company, based in Mountain View, California.

Gamma, based in Andover, England, did not respond to seven emails. The company has ignored repeated questions from The Associated Press for more than a month.

Gamma's FinFisher is one of many corporate-made viruses which have attracted scrutiny after the wave of Arab revolutions exposed the high-tech tools used by repressive regimes to stifle dissent. FinFisher — which can log keystrokes, record Skype calls, and turn webcams and cellphones into improvised surveillance devices — drew particular attention after a sales pitch for the spyware was discovered in an Egyptian state security building in 2011.

Citizen Lab, a research group based at the University of Toronto's Munk School of Global Affairs, has since linked FinFisher to servers in 36 countries and found the virus hidden in documents including news updates from Bahrain and photographs of Ethiopian opposition figures. In a report published late Tuesday, Citizen Lab said that it had also found a FinFisher sample hiding in a document about Malaysia's upcoming general election.

Citizen Lab's Morgan Marquis-Boire said the evidence fell short of proving that FinFisher was being used by one government or another, but said its dispersal hinted at the global reach of espionage programs.

"It really shows the ubiquity of this type of software," he said.

That ubiquity has already given Gamma a public relations headache. In March, the company was identified as one of five "corporate enemies of the Internet" by journalists' lobbying group Reporters Without Borders. Earlier this month the rights group Privacy International sued the British government over allegations that Gamma had illegally exported its surveillance technology — an accusation the company has denied.

A British legal expert said Mozilla's intervention could spell new trouble for Gamma.

The fake Firefox information attached to the FinFisher software was "deliberately designed to be read and mislead," said Simon Ayrton, a partner at specialist intellectual property law firm Powell Gilbert. He predicted that Mozilla would have a strong case if it sought an injunction against the spyware maker.

"I'd be surprised if FinFisher attracted much sympathy from the court," he said.

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Online:

Mozilla: http://www.mozilla.org/

Citizen Lab's report: https://citizenlab.org/2013/04/for-their-eyes-only-2/

Gamma Group: https://www.gammagroup.com/

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Raphael Satter can be reached at: http://raphae.li/twitter