Acer on Sunday unveiled the world's thinnest laptop computer as an array of "ultrabook" rivals prepared to debut this week at the Consumer Electronics Show in Las Vegas.

The Taiwan-based computer titan will begin shipping Acer Aspire 5 models in the second quarter of this year, with prices to be disclosed in coming weeks.

"That S5 is quite significant," analyst Tim Bajarin of Creative Strategies said after the Acer press event.

"It looks like the thinnest and lightest, and it sets the bar for the rest of the ultrabook vendors," he continued.

The Aspire S5 has a 34-cm (13.3-inch) screen and is 15 mm at its thickest point. The ultrabook weighs slightly less than 1.35 kg (three pounds).

"We are committed to evolving this technology," said Acer chief executive J.T. Wang. "By the second quarter of this year we will have four models of ultrabook and more to come."

Ultrabooks powered by Windows 8 will be released by Acer after Microsoft releases the new version of its computer operating system later this year, according to Wang.

He estimated that ultrabooks would make up at least 35 percent of the Acer product line by the end of this year.

Since Aspire S5 is Windows based it is not likely to be a direct challenge to MacBook Air laptops, which have been winning converts to the sleek machines powered by Apple software, according to Bajarin.

"The real battle is not with Apple, it is with all the other vendors coming out with Windows ultrabooks," Bajarin said.

"Apple will still do great with MacBook Air, but in the Windows world it is great news that five years after Apple set the tone the industry is finally getting something equal," he continued.

Acer also announced plans to launch a free service that will let users of its computers store video, photos, music, and documents in the Internet "cloud" and access files from any Windows 8 or Android software powered gadgets.

"We believe Microsoft will take care of Windows devices; Google will take care of Android devices, and Acer will take care of in between," Wang said.

"We will make Windows work very well with Android and other platforms too."

Bajarin described Aspire S5 as the first viable Windows equivalent of popular MacBook Air laptops built by California-based Apple.

Acer Cloud appeared to be a Windows version of the Apple's freshly-launched iCloud service that lets people access their content from iPads, iPhones, iPods, and Macintosh computers, according to the analyst.