Silicon Valley venture capital firm Kleiner Perkins Caufield & Byers is doubling the size of its fund for iPhone application developers, as it eyes new opportunities with the forthcoming launch of Apple's iPad.

Kleiner Perkins said its so-called iFund investment pool now totals $200 million. The firm said the new money was not carved out from other funds, but instead represents fresh capital.

The iFund was originally launched in 2008 with a total of $100 million, which is now committed to 14 app development companies. Those companies have also raked in an additional $330 million from other investors, Kleiner Perkins said.

The iFund has invested in popular app companies such as game designer ngmoco, texting provider Pinger, and music discovery service Shazam.

There are more than 140,000 different apps available for Apple's iPhone and iPod touch, and Apple's App Store has proved to be an important sales driver for those devices.

Users have downloaded more than 3 billion apps, many of them free programs, covering a huge range of uses, from productivity tools to time-wasting entertainment.

Apple's iPad tablet is set to launch in the United States this Saturday. The device uses the same operating system as the iPhone and will be able to run almost all the same apps.

Kleiner Perkins partner John Doerr, a renowned figure in the VC world, said: Saturday is just the beginning. IPad is where the revolution is happening.

Many app developers are already hard at work overhauling existing programs or designing new ones to take advantage of the iPad's 9.7-inch touchscreen.

Kleiner Perkins said the iPad will ship with 11 apps from iFund-backed companies, with 20 more in development.

Apple Chief Executive Steve Jobs said in a news release: Kleiner Perkins has done a terrific job at finding, funding and supporting great iPhone app developers. We are thrilled that they are doubling the size of their fund, along with expanding it to now include iPad developers too.

(Reporting by Gabriel Madway and Poornima Gupta; Editing by Gary Hill)