Google has launched an audacious attack on Microsoft, announcing laptop computers called Chromebooks that will use its own operating system – rather than Windows – will ship in June.

The machines will be made by Samsung and Acer, two companies that have previously made machines running Microsoft's software.

The laptops will coordinate tightly with Google's "cloud" online services, and have almost no capacity to store information. Instead, the bare-bones operating system is essentially a web browser that steers users to applications like email and spreadsheets directly on the web, rather than storing software such as Outlook or Word directly on PCs.

The move is Google's first directly onto Microsoft's home turf of PC operating systems and the Office suite software – a pair of monopolies that generate around $5bn of profits for the company every quarter. Until now it has largely avoided direct competition with Bill Gates's company on its strongest areas, focusing instead on internet areas such as search and webmail and online document services.