BlackBerry defended the security of its smartphones after The Guardian reported that a British agency penetrated the devices at Group of 20 meetings in 2009 to monitor phone calls and e-mail traffic.
Evidence of the monitoring came from top-secret documents that American Edward Snowden showed The Guardian.
The documents, which the paper said belonged to the intelligence arm known as Government Communications Headquarters, tout success in reading BlackBerry traffic. One excerpt titled "BlackBerry at G20" reads: "Delivered messages to analysts during the G20 in near real-time."
Canada-based BlackBerry said: "We remain confident in the superiority of BlackBerry's mobile security platform for customers using our integrated device and enterprise server technology. There is no 'back door' pipeline to that platform."
The company said it couldn't comment on media reports of government surveillance.
BlackBerry has built a following among lawyers, bankers and government workers because of the security of its devices and the fact it operates a network of servers on behalf of its clients. The company is counting on that reputation as it seeks to claw back market share lost in recent years to Apple and Samsung.
"We never comment on security or intelligence issues and I am not about to start now. That would be breaking something that no government has previously done." British Prime Minister David Cameron told broadcasters at the G8 summit in Northern Ireland.
Snowden's disclosures to The Guardian and Washington Post forced the US administration to confirm the existence of two surveillance programmes, one designed to collect phone call records from millions of US citizens and another that monitors the internet activity of foreigners.