US software giant Microsoft sold 4.3 million Xbox 360 video game consoles (pictured) in the last three months of 2007, helped by hit titles such as Halo 3 and Mass Effect, according to company data.

But the firm also said it was "disappointed" with problems that had plagued its online gaming service for days and offered a free downloadable game to more than eight million worldwide users of the network.

A total of 17.7 million Xbox 360s had been sold worldwide since it first went on sale in late 2005, Microsoft said. Earlier sales data from the software giant showed 13.4 million consoles sold by the end of September.

"Holiday 2007 was a blockbuster season for the gaming industry," Microsoft said, adding that the Xbox 360 has kept its lead over rivals in terms of total dollars spent on hardware and software.

Microsoft competes against Nintendo's wildly popular Wii and Sony's PlayStation 3 consoles for dominance in a global video game industry that is thought to have approached $40 billion in revenue in 2007.

Nintendo and Sony have not released holiday sales figures for their machines, but by the end of September, about 13.2 million Wiis and 5.6 million PS3s had been sold globally. Microsoft has counted on its Xbox Live online service to set its console apart from rivals. The service lets users download hundreds of games, as well as TV and movies.

But gaming Web sites and forums have been filled in recent days with complaints from users frustrated by not being able to sign on to the service or play online.

Xbox Live general manager Marc Whitten said the problems stemmed from a "massive increase" in new users of the service over the holiday season, when sales of video game hardware and software surge.

"While the service was not completely offline at any given time, we are disappointed in our performance," Mr Whitten said, adding that Wednesday had set a record for the number of users signed on simultaneously.