Apple Inc CEO Steve Jobs on Thursday revealed stronger-than-expected sales of 450,000 for the iPad since its much-hyped debut, and touted a phone operating system with a new advertising platform to compete with rival Google Inc's.

Analysts expect sales of 1 million units or more for the iPad -- touted as a new class of gadget that will bridge laptops and smartphones -- in the current quarter ending June, and roughly 5 million in 2010, though estimates vary widely.

We're making them as fast as we can, our ramp is going well, but evidently we can't quite make enough of them yet so we're going to have to try harder, Jobs said, noting iPad sell-outs at Best Buy stores.

The electronics giant has staked its reputation on the 9.7-inch touchscreen tablet. It is helping foster a market for tablet computers that is expected to grow to as many as 50 million units by 2014, according to analysts.

I think it's pretty impressive, five days almost half a million units, and it shows there's still pretty good momentum behind the first day, said Gartner analyst Van Baker.

Despite some critics who question whether a true need exists for such a gadget, analysts expect Hewlett-Packard , Dell and others to trot out competing devices of their own this year.

Since going on sale on April 3, users have downloaded 600,000 digital books and 3.5 million applications for the iPad, Jobs said. There are already 3,500 apps available for the iPad.

It was above my expectations, frankly, said Joe Clark, managing partner of Financial Enhancement Group, referring to iPad sales.

The day the original Apps Store launched it was a game change for the iPhone and it will do the same eventually for the iPad.

At a media event at the company's Cupertino, California, headquarters, Jobs said Apple had so far sold more than 50 million iPhones, the smartphone that competes with Research in Motion's Blackberry and Motorola's Droid.

Apple is expected to launch the fourth-generation model of its iPhone, which was introduced in January 2007, later this year.

Jobs, looking thin but energetic, said the forthcoming iPhone 4.0 operating system -- also available on iPads this fall -- will carry its new iAd mobile advertising platform, marking the company's foray into a small but burgeoning market.

IAds will allow applications developers to use advertisements in their apps, pocketing 60 percent of the revenue. Apple will sell and host the ads.

Jobs harshly criticized the current manner and look of mobile advertising, particularly search ads. He promised that iAds will foster more engaging advertising that will not pull users away from the content within apps.

Tim Bajarin, president of consulting company Creative Strategies, said it was a dramatic shift in thinking about the delivery of mobile advertising, and an obvious move by Apple to set itself apart from Google, which has made its name on search ads.

It's very clear that Jobs believes that ads in the context of apps makes more sense than generic mobile search, he said.

Apple's entry into the mobile ad arena had been widely expected. This year, it paid $270 million for Quattro Wireless, an advertising network that spans both mobile websites and smartphone applications.

Google, which already sells advertising on smartphones, agreed to buy mobile ad firm AdMob late in 2009. U.S. regulators are examining the deal's antitrust implications.

Research group Gartner expects the mobile advertising market to expand by 78 percent to $1.6 billion in 2010.

Jobs also said the new operating system will include support for multitasking -- addressing a perennial consumer complaint -- allowing users to switch between several programs running simultaneously.

Shares of Apple turned positive briefly after Jobs' announcement before quickly dipping back into negative territory. They closed 0.3 percent lower at $239.94 on the Nasdaq.

(Writing by Edwin Chan; Editing by Steve Orlofsky, Leslie Gevirtz and Matthew Lewis)