Sprint Nextel said on Friday that sales of Apple Inc iPhones surpassed its expectations and that iPhone 4 and iPhone 4S broke the device family one-day sales record for the No. 3 U.S. mobile service.

Sprint, the third U.S. operator to carry iPhone, is under pressure to sell a lot of iPhones as investors have been fretting over how it will pay for the higher subsidies that carriers pay for Apple products. Sprint was heavily criticized for failing to comment on its iPhone costs at an analyst day last week.

Sprint today reported its best ever day of sales in retail, web and telesales for a device family in Sprint history with the launch of iPhone 4S and iPhone 4, Fared Adib, Sprint product chief, said in a statement.

Without giving specific numbers, Adib said Sprint reached the milestone at about 1 p.m. EDT on the day of the iPhone 4S store launch. It started taking preorders on October 7.

The response to this device by current and new customers has surpassed our expectations and validates our customers' desire for a truly unlimited data pricing plan, he said.

Apple's new iPhone went on sale in seven countries around the globe on Friday, prompting long queues at many stores from Sydney to Tokyo to New York.

Sprint shares closed up 1 cent at $2.79 on the New York Stock Exchange. The shares edged up to $2.80 in after-hours trade.

(Reporting by Sinead Carew; editing by Matthew Lewis)