Queues of hundreds formed for the new iPhone launch in Japan
Apple has revealed as part of its quarterly earnings statement that it cannot produce the new iPhone 3GS fast enough.
Speculation has arisen in recent days that demand was outstripping supply.
"The demand has been staggering almost in every country that we've shipped in," said the firm's chief operating officer Tim Cook.
Nevertheless, the firm still plans to launch the device in 20 more countries in August.
The firm said in a conference call that it sold 5.2 million iPhones in the quarter, seven times more than a year earlier. Apple reported higher-than-expected results, largely based on sales of the handsets.
"We are currently unable to make enough iPhone 3GSs to meet robust demand, and we're working to address this," said Apple's chief financial officer Peter Oppenheimer in a conference call about quarterly earnings.
Mr Cook noted that the recent increase in production of the handset was "right on schedule" and would be enough to meet the projected demand when the handset launched in more markets.
"We are confident enough in the production ramp that we will be launching about 20 additional countries on 22 August - which would bring our total to over 40 - and we still expect to be selling the iPhone in over 70 countries later this calendar year," he said.