"Looks like it's a pretty productive Friday for #iPad owners," tweeted Microsoft chief Satya Nadella. He also attached a picture with his tweet that reveals Word, Excel, and PowerPoint as the top three most popular applications on Apple App Store.

At a news conference on Thursday, executives demonstrated a new ‘touch-first’ version of Office crafted for the iPad, available for download as a free app, though a subscription is needed to let users create or edit documents rather than just read them.

Nadella gave no indication of when Microsoft would release ‘touch-first’ versions of Office apps for Windows 8, the latest version of the operating software, which he acknowledged had fallen behind in the mobile era.