Microsoft will discontinue extended support for the 12-year old XP in April, ending provision of regular security patches and technical assistance for the operating system

However, with less than 100 working days to go, a study from Ascentius Consulting shows that penetration of XP is still in the region of 40% to 70% in the Indian banking sector, leaving some 34,115 public sector undertaking (PSU) branches at risk.

Microsoft says that the consequences could be huge for branches in rural areas, where systems may go down, denying customers access to services. Even in urban branches, more than half of customers could see waiting times of up to 30 minutes when carrying out transactions.

The study estimates that banks could pay a heavy financial price, losing up to Rs1100 crore a day in lost business. Customers may also lose out because they will be at risk of ID theft and fraud.

Among the other problems banks will face if they do not upgrade operating systems is an inability to support new biometric devices which are required by the central bank and are being used by the government to distribute benefits in rural areas.

Amrish Goyal, GM, Windows Business Group, Microsoft, India, says: "We have been advising our customers to move off Windows XP for a long time now. There are a significant number of PCs out there that still need to be moved per a plan. The move to a modern OS like Windows 8.1 will not only alleviate the risks for users and businesses but will also open up opportunities posed by modern technology, like the cloud, for them."

Last month America's Federal Financial Institutions Examination Council issued its own XP warning, telling banks and technology vendors to make sure that they move PCs and other hardware such as ATMs to Windows 7 or Windows 8. According to some reports, up to 75% of US ATMs are still running on XP.