Google on Tuesday unveiled plans to help develop the watches and other wearable computers based on its Android mobile operating system, which already runs more than three out of four smartphones sold worldwide. The Android Wear project is open to software makers to create apps for the watches, putting Google at the forefront of efforts to jumpstart the nascent wearable computing market.

The news comes as speculation swirls around iPhone-maker Apple Inc's plans for wearable computers, including a smartwatch of its own. Apple chief executive Tim Cook has promised new "product categories" later this year.

LG Electronics also said on Tuesday it would introduce its first Android watch, the G Watch, in the second quarter. Motorola said its Moto 360 Android watch would be available this summer. Fossil Group Inc, which makes watches, handbags and other accessories, also announced that it was working with Google on Android devices.

Motorola said it would share more details about its forthcoming Moto 360 smartwatch when it holds a special online press conference on Wednesday. Google recently announced plans to sell its Motorola business to Chinese PC-maker Lenovo Group Ltd.

Samsung was among the first to sell a smartwatch for consumers, but its maiden effort, the Galaxy Gear, was widely panned by reviewers.

Juniper Research expects more than 130 million smart wearable devices will ship by 2018. Moreover, global shipments of wearable "smart glasses" alone will reach 10 million each year by 2018, compared with an estimated 87,000 in 2013, according to the research firm.