Numbers have doubled in the last five years, says the Association of Technology Staffing Companies (ATSCo), which obtained the figures from the Home Office.
ATSCo believes this could be the first evidence of 'onshore offshoring', a phenomenon already noted in the US, where companies in the developed world recruit staff from less-developed economies - without upgrading their salaries to western levels. Experienced programmers in India earn a fifth of their UK counterparts' salaries, according to pay monitoring firm PayScale.
The onshore offshoring practice sparked a political fracas in the US, culminating in the US cutting temporary work visas by a third in 2003.
Ann Swain, chief executive of ATSCo, says: "Skill shortages continue to be a major pull factor in bringing foreign IT workers to the UK, but the concern is that some organisations may be taking advantage of the visa system to import cheap labour."
Companies should invest in training UK workers rather than rely on overseas skills, maintains Swain.