Apple iPhone 5c phones are pictured at the Apple retail store on Fifth Avenue in Manhattan, New York Sept 20, 2013. [Photo / Agencies]

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Demand for the iPhone 5S has exceeded initial supply and many online orders are scheduled to be shipped in the coming weeks, Apple said. On Friday, long lines formed outside stores in Tokyo, New York, San Francisco and other cities for the new top-of-the-line 5s and the less-expensive 5c. It was the first time Apple launched two iPhone models simultaneously.

The gold-colored version of the 5S, which also comes in silver and gray, was sold out as of Friday and will now ship only in October, according to Apple's website. As of Monday, the two other colors were also set to be shipped only in October.

"Thanks to all our amazing customers for the fantastic weekend!" said Cook in his second tweet, after he joined Twitter following a visit to Palo Alto Apple store last Friday.

Apple also said gross profit margin would come in near the top of a range of between 36 percent to 37 percent, in line with average forecasts for 36.7 percent. The more optimistic margin forecast should allay investor concerns that, at just $100 less than the 5s, the 5c will draw buyers away from the premium gadget.

Analysts' average revenue forecast for the quarter stands at $36.1 billion, according to Thomson Reuters I/B/E/S.

Apple, which had grown notorious for providing conservative estimates that it routinely overshot, had resolved to improve its guidance for investors. Analysts have said the change will help rein in some over-the-top financial expectations.

The company said more than 200 million iOS devices are now running iOS 7 mobile software, rolled out just before the iPhone launch.

Apple did not break out separate sales figures for the 5S and 5C. The 5C, which starts at $199 with a contract, offers a touch ID that scans a user's fingerprint to unlock the phone. The 5C starts at $99 and comes in five colors.

"If Apple could ship so well without even having a larger screen iPhone, which we think it could deliver next year, then Apple is getting over a key hump," Shebly Seyrafi, an analyst with FBN Securities, said in a note to clients. "We believe that the immediate availability of the phone in China is also a key driver of the strength."

Earlier reports

Lukewarm Chinese market weigh down Apple-related shares

Apple brand goes stale in China

Apple Inc to sell new iPhones in China

Apple's 'low-end' phone price disappointing

Hands-on: Impressions of iPhone 5S, iPhone 5C

Colorful iPhone, not attractive enough?