Microsoft is in advanced discussions about purchasing Skype, the internet telephone company, a person close to the company said, in what would be one of the technology company’s largest deals as it seeks to revitalise its business.

A deal between the two companies could be announced as early as Tuesday, according to the person familiar with the talks. While details were still hammered out on Monday night – which could yet derail an announcement – the person added that the deal could value Skype at about $8.5bn, including debt.

The deal would mark Microsoft’s most aggressive move online so far, as the Seattle-based company seeks to respond to strategic challenges and shift away from its core Windows business into other areas, including the internet, communications and entertainment.