By Josh Ong

Published: 02:15 AM EST (11:15 PM PST)

Apple had originally planned a 2011 release for an LTE-capable iPhone, but has pushed back its timeline for the device because of production constraints, according to a new report out of the Far East. Meanwhile, sources indicate that China Mobile will likely begin selling Apple's next-generation iPhone later this year.

According to DigiTimes, industry sources said that "problems concerning yield rates of LTE chips offered by Qualcomm" have reportedly forced Apple to delay a planned upgrade of the iPhone to support 4G LTE networks.

"Apple is likely to delay the launch of its LTE-enabled iPhones to 2012, said the sources, noting that the industry had also long been skeptical about the launch of LTE iPhones in 2011 as the implementation of LTE networks has not yet matured," the report noted.

Apple Chief Operating Officer Tim Cook told investors last month that the company was unwilling to go with early LTE chipsets. "The first generation of LTE chipsets force a lot of design compromises with the handset, and some of those we are just not willing to make," he said during the company's earnings call for the second quarter of fiscal 2011.

Executives from both China Mobile and Verizon have indicated that Apple has expressed interest in LTE, though they were unable to reveal specific timing. "You'll see more coming from Apple on LTE," Verizon Wireless CEO Daniel Mead said in February, shortly after the launch of the Verizon iPhone 4. "They understand the value proposition of LTE and I feel very confident that they are going to be a part of it."

China Mobile Chairman Wang Jianzhou said in March that Apple CEO Steve Jobs "has expressed his interest in an LTE iPhone and is willing to start the development at an early date."

According to DigiTimes, China Mobile, which operates the world's largest mobile network with over 600 million subscribers, "is expected to reach an agreement with Apple to sell iPhone 4S smartphones in China in September at the earliest."

Apple has yet to truly tap the Chinese mobile market, though it has be "on a tear" in the country. According to Cook, iPhone sales in Greater China grew by almost 250 percent year over year in the second quarter of fiscal 2011.

Given China Mobile's size, Apple will need to partner with the carrier in order to continue to expand in the world's most populous nation. Cook said in April that Apple is "constantly looking at where we should bring on incremental partners," while admitting that the company's iPhone focus has been on China.

Jeffries & Co. analyst Peter Misek suggested last week that Apple will release a new iPhone this September, instead of during the summer as in years past. China Mobile, Sprint and T-Mobile are expected to be added as carriers.

Analyst Brian White of Ticonderoga Securities said last month that Chinese sources had indicated the next-generation iPhone is on track to launch in October of this year.

China Unicom has been Apple's exclusive partner in China since the launch of the iPhone 3GS in 2009. Reports emerged in February that Apple's CDMA iPhone 4 will see a limited launch on the third-place China Telecom network in June.