NEW DELHI (AFP) - Fugitive intelligence contractor Edward Snowden worked briefly at the US embassy in India almost three years before revealing the scale of his country's surveillance programmes, according to a report on Monday.

The former National Security Agency (NSA) contractor arrived in New Delhi in September 2010 "to assist as a technical expert" at the US embassy, according to Foreign Policy magazine.

The American magazine, citing an unnamed source, did not say what Snowden was working on at the embassy during his short stay in the Indian capital.

The embassy in New Delhi did not immediately respond to an AFP request for comment or confirmation.

Snowden sent shockwaves around the world last year by revealing the extent of Washington's electronic eavesdropping.

The 30-year-old former contractor leaked explosive details of the secret surveillance schemes to media including the Washington Post and Britain's Guardian, and has fled the US to avoid prosecution.

While in Delhi, Snowden undertook a six-day "ethical hacker and security analyst" course, according to a spokesman for the company that ran the course.

Snowden had contacted Koenig Solutions in 2009, wishing to take a course during his business visit the next year, spokesman Somit Biswas told AFP.

Snowden paid some US$2,000 (S$2,528) for tuition, food and lodging from his personal account, which he said would be reimbursed, Biswas said.

He started another course in JAVA before cutting halting midway through, saying he had to leave the country for medical reasons, Biswas added.

Snowden's leaks have deeply embarrassed President Barack Obama's administration by revealing the massive scale of America's spying efforts.

He arrived in Russia in June last year as a fugitive and spent more than a month holed up in a Moscow airport before being granted a year's asylum.

US federal prosecutors have filed a criminal complaint against him, charging him with espionage and felony theft of government property.