The survey by the security firm McAfee and the National Cyber Security Alliance also found disparities between Americans' concerns and their practices in warding off attacks.

It found 90 percent of Americans agree that a safe and secure Internet is crucial to economic security and the same number do not feel completely safe from viruses, malware and hackers while on the Internet.

But 64 percent percent of those surveyed said they have never any installed security software or apps to protect against viruses or malware.

The survey found 49 percent of smartphone users have used their device to access the Internet, but 58 percent have not backed up their data.

NCSA, a non-profit public-private partnership, unveiled the survey to kick off the ninth annual National Cyber Security Awareness Month.

"The threat to the safety of Americans online is growing every day and, as the survey shows, the fear of Americans has also grown to 90 percent," said Gary Davis, vice president of global consumer marketing at McAfee.

"It is our responsibility to make sure that consumers are aware of these growing threats, so they can be best prepared to defend themselves against these hidden criminals."

The browser became available for download at 1300 GMT and offers a relatively minimalist Russian-language interface based on the WebKit platform and Google's Chromium code.

The "cloud-based" browser "integrates the best of our products and services and is open to other web developers," Yandex CEO Arkady Volozh said in the official company statement.

It incorporates the anti-virus technology of Russian security company Kaspersky Lab and "considerably expands the browsing territory for those who speak only one language," the statement said.

The browser's logo, a white sphere with a red "Y" stretching across it, was instantly nicknamed "the thong" by Russians commenting the company's announcement on Facebook.

Yandex is the world's fifth-largest search engine that claims over 25 million daily visits to its main page Yandex.ru.

Like Google, it also offers an array of services from email to blogs and web storage, as well as a popular page for navigating Moscow's traffic jams and an electronic money system.

Despite the advancement of Google, which now holds a quarter of all Russian searches, 15-year-old Yandex is still far ahead with about 60 percent of the share, and had a successful public listing in 2011.

The company clashed with Google earlier this year when founder and CEO Volozh, who also holds a stake of just under 20 percent in Yandex, accused the US company of being anti-competitive by making it difficult to use other search engines with its browser Chrome.

"Two years ago... everyone started eating everyone else. Google began advancing its Chrome browser and actively pushing out competitors from it," Volozh said in an interview to Vedomosti Monday.

"If the product is good, then our share will grow," he said.