Barcelona, Spain (CNN) -- Mozilla announced Sunday it will launch handsets running its new Firefox mobile operating system, pitting itself directly against Apple and Google.

The nonprofit company made the announcement at a news conference on the eve of the world's largest mobile technology show, Mobile World Congress in Barcelona, Spain, under the new marketing slogan "Unleash the fox."

The company says it is partnering with 18 network operators and four handset manufacturers around the world to launch handsets running its open-source mobile operating system, which it also demonstrated Sunday.

Alcatel, LG and ZTE will be first to build the first Firefox OS devices, with Huawei to follow later in the year, a spokesman said.

When cellphones were hideous

The company said the first wave of Firefox devices would go on sale beginning in July in Brazil, Colombia, Hungary, Mexico, Montenegro, Poland, Serbia, Spain and Venezuela.

What features would you like to see?

The new software is built on open Web standards and is capable of operating on much less sophisticated devices than many existing smartphones, the company says.

"Firefox OS will break down the walls between apps and the Web because Firefox OS apps are built using Web technologies, like HTML5," said Jay Sullivan, Mozilla's senior vice president of products.

"We expect to see lots of amazing apps people love built for Firefox OS because more developers are already creating for the Web than for any other platform."

Developers will be free to build and sell mobile applications for the operating system without having to share revenue with Apple or Google.

NYPD dedicates squad to phone thefts

John Jackson, vice president of the research company IDC, said, "The impressive lineup of operators who have now pledged to distribute Firefox OS devices speaks clearly and powerfully to the platform's potential and points to 2013 being a breakout year for Mozilla in the mobile domain.

However, Stuart Miles, editor of gadget review site Pocket-lint, said while there was potential for success in developing countries, the company faced an uphill struggle against the established big players.

"It's an interesting move, mainly because I think the people that are backing it are doing so to either hedge their bets or to provide leverage against the bigger players.

"The idea of HTML web apps is one that Apple had five years ago with the launch of the iPhone but soon realized that they could make much more money by charging for apps rather than giving them away for free. As an organization, Mozilla doesn't have those concerns."

Sleep texting is a thing

Mozilla says operators who have committed to devices include América Móvil, China Unicom, Deutsche Telekom, Etisalat, Hutchison Three Group, KDDI, KT, MegaFon, Qtel, SingTel, Smart, Sprint, Telecom Italia Group, Telefónica, Telenor, TMN and VimpelCom.