Microsoft, the US software giant, has said its quarterly revenue will be higher than previously expected.

The announcement, which came late on Wednesday, combined with better than expected results from Motorola and Yahoo to send tech shares higher in world markets.

Microsoft shares were up 6% in electronic trade after the US markets closed.

But the good news for investors was tempered by news that the company would report its first-ever investment loss, of $2.6bn.

Microsoft said operating profits for the fourth quarter - which ended on 30 June - were in line with expectations, excluding the investment losses.

"Core revenue growth for the quarter was strong and reflects consumer enthusiasm for our products and services despite a slowing economy," said chief financial officer John Connors.

Cable and telecoms losses

Microsoft said quarterly revenue would reach $6.5bn-6.6bn, up from previous forecasts of $6.3bn-6.5bn.

The $2.6bn charge came from losses in cable and telecoms investments.

Total investment losses were $3.9bn but this was offset by gains from interest, dividends and other equity interests.

The company is due to report results on 19 July.

Windows revamp

Also on Wednesday, Microsoft said it would revamp its next-generation Windows operating system to make it easier for rival companies' products to compete.

The move follows a recent US Court of Appeals ruling that Microsoft agreements with computer manufacturers had broken competition law.

The court stopped short of requiring the company's break-up but Microsoft's latest move is being seen as an attempt to head off such action.

Some analysts say many Microsoft products have already achieved such dominance that Wednesday's announcement will have little practical effect.

But the decision should mark an end to the practice of requiring computer manufacturers to display Microsoft products such as Internet Explorer on the desktops of new computers.