Software giant Microsoft is facing serious growing threats to its monopoly in the UK public sector following admissions from local authorities that they plan to increase their adoption of open-source software. The inroads against the world�s largest software company emerge just as the UK government is set to promote open source to public bodies, championed by Linux, while the movement itself begins to mature. In a survey of 100 local authorities for the Financial Times, over 60 per cent said they intended to step up their use of open source software, compared to just one per cent predicting a decline. Cost reductions were cited as the key reason in favour of open source, meaning the switch to Linux is seen as an enabler to achieve efficiency savings spelled out by the Gershon Review. Public sector managers also believe migrating to the open source movement � 42 per cent are planning to do so - will deliver the interoperability they need, while a lesser number cite the support and quality of the product. Already converted managers meanwhile claim that Linux and its bedfellows are less vulnerable to virus attacks, while being able to retain similar functions as a Microsoft product.