Amazon.com will launch its own smartphone in the fourth quarter of 2012, Citigroup said, citing its supply-chain channel checks in Asia.

In a research note dated November 17, Citigroup researcher Mark Mahaney wrote: "Based on our supply chain channel checks in Asia ... we believe an Amazon Smartphone will be launched in 4Q12." The brokerage added that it believed the online retail giant is now jointly developing the phone with cellphone maker Foxconn.

"With the clear success of the Kindle e-Reader over the past 3 years, and Kindle Fire possibly succeeding in the low-priced tablet market, we view this as the next logical step for Amazon," the brokerage said.

The brokerage expects the smartphone to adopt a Texas Instrument OMAP 4 processor and Qualcomm's baseband chips.

Citigroup also suggested the device would cost $150 ~ $170 to build, and might be sold for about that amount. Amazon is selling the Kindle Fire tablet at $199, which is $10 less than research firm iHS determined was the $210 cost of building the device.

Amazon officials did not respond to a request for comment.