Adobe Systems Inc is halting development of its popular Flash Player for use in mobile browsers, essentially admitting defeat to rival Apple Inc in a long-running battle over Web standards.

The decision by the software maker, whose shares fell nearly 12 percent, means that Web developers will probably stop using its Flash tools to produce video, websites and applications for delivery over mobile browsers. That would be a relief for tens of millions of iPhones and iPad users whose browsers are not capable of viewing content built in Flash, but it could hurt sales of Adobe's tools for developing websites.

Instead, Adobe said it will focus on selling tools for website developers that use an emerging set of Internet standards known as HTML5, which Apple has long promoted.

Shares of Adobe were down 11.7 percent at $26.88 in morning trading.

(Reporting by Jim Finkle. Additional reporting by Yinka Adegoke; Editing by Lisa Von Ahn)