Google could undermine its long-term strategy of extending its reach into mobile Web services if it chooses to go head-to-head with cellphone manufacturers that are using its Android operating system.

Analysts say Google's ultimate success rests on phones of all sorts using its web search and services - the lion's share of its revenue - a goal that Google could jeopardise by offering a mobile phone that competes against those of its partners.

Google, which sources say will push out its own phone as early as 2010, may be making a multibillion-dollar mistake and should focus on getting its Android operating system software on as many phones as it can, to draw in consumers for its bread-and-butter web search and services.

Google is "going to box themselves more and more in a corner by actually making these phones," said Anil Doradla, an analyst with William Blair & Company.

With details scarce for now, analysts struggle to understand Google's move into a highly competitive business in which it has no experience.

Some say the world's No. 1 internet search engine is trying to temper Apple's dominance in the smartphone market as it tries to publicise Android.

Phones using Google's Android smartphone software - announced this year - have lagged Apple's iPhone in sales and reputation, and the search leader's decision to make its own hardware device could solve that problem.

Unlike Apple, whose roots in the hardware design business helped its entry into the cellphone market, Google's has expertise in web-based software that may not necessarily translate into consumer electronics prowess.

Conversely, smartphone software like Android ensures that the company's advertising-based web services get prominent placement on the new breed of mobile devices and could give Google better access to valuable data, like a person's location, which can be used to sell targeted ads for a premium price.

Google has had early success convincing phone makers to adopt its Android software. Android is currently available on more than 12 different phones from vendors including Motorola Inc. and Samsung, with more devices coming from Sony-Ericsson, LG Electronics and Acer.

That support may fade as Google moves forward with plans to develop its own, Google-branded Android phone to be sold directly to consumers, as a source familiar with the matter said the company is doing.

"If the most essential element of your phone is coming from a competitor, it's not good. Not in any industry," said Mr Doradla, in reference to phone makers that are currently using Google's Android software.

Signal Hill Group analyst Todd Greenwald said Google, which has a market cap of $189 billion and roughly $22 billion of cash and securities, may figure it is big enough that it can risk upsetting certain partners.

Motorola, which is struggling to mount a comeback and has built its new line of phone products around Android, does not appear to have many alternatives, said analysts. An official from Motorola was not immediately available for comment.

At least one wireless carrier appears to be on board with Google's strategy: Deutsche Telekom's T-Mobile USA is set to offer a subsidised version of the Google phone to US consumers who agree to a wireless service contact with the carrier, according to the person familiar with the matter. Among the other questions raised by Google's move are how an internet company will fare in the hardware market.