The bitter rivalry between Samsung and Apple will expand beyond smartphones and tablets to smart wristwatches next month with Samsung first to market on 4 September with a device called the Galaxy Gear.

Due to be unveiled just before the start of the IFA consumer electronics trade show in Berlin, the device is likely to connect wirelessly to a smartphone to access the internet.

It is thought to be able make voice calls, access emails and surf websites.

Although an on-sale date has not been confirmed, the Galaxy Gear is almost certain to beat Apple's long rumoured "iWatch" to market, although it will not be the first smartwatch to go on sale.

Sony's second device, the SmartWatch 2, went on sale earlier in the summer. US startup Pebble Technology, meanwhile, raised $10.3m (£6.6m) via crowdfunding to make its Pebble smartwatch, which has been pre-ordered by more than 275,000 people.

Research firm Canalys expects more than 500,000 smartwatches to be sold this year, followed by 5m in 2014 as Samsung, Apple, Google and other technology companies launch their own models.

Frequent leaks and patent filings have hinted at these companies' plans. Apple is thought to have a 100-strong team working on its smartwatch, and in June applied for the iWatch trademark in Japan.

The flurry of activity is part of a wider excitement within the consumer electronics industry about wearable gadgets, which also include wireless fitness tracking devices such as the Fitbit and Nike's FuelBand, and eyewear comparable to Google Glass.

Research firm Juniper Research expects more than 18m smart wearable devices to be sold in 2013, rising to 170m by the end of 2018.