Russian hacker Mikhail Shargin allegedly helped cheating by 820 students by working on the online system in 2001's JEE-Mains, reports ndtv.com.

The CBI made this disclosure on Tuesday in a Delhi court which gave the agency two-day custody of the 25-year-old.

The examination taken by over 9 lakh students last September is conducted only on control-restricted computers.

Shargin hacked into the system which would have helped students grant "remote access" to his aides, who then answered the questions on computers.

24 people have been arrested in the case so far.

The CBI had on Monday detained Shargin at Indira Gandhi International Airport in connection with its probe into alleged manipulation of JEE (Mains) examination last year. officials said Monday.

The central agency had issued a 'Look Out Circular' against the foreign national, suspected to be main hacker, for alleged manipulation of the prestigious examination, they said.

The Central Bureau of Investigation (CBI) was alerted by the central agencies when the Russian national arrived at the airport from abroad, they said.

He was immediately detained by the CBI and is being questioned in connection with the JEE manipulation case probed by the agency, they said.

Sources said the suspect might be taken into custody.

In September last year, the agency had booked Affinity Education Pvt Ltd and its three directors, Siddharth Krishna, Vishwambhar Mani Tripathi and Govind Varshney, besides other touts and associates for alleged manipulation of examination.

It was alleged that the three directors, in conspiracy with other associates and touts, were manipulating the online examination of JEE (Mains) and facilitating aspiring students to get admission into top National Institutes of Technology in consideration of huge amounts by solving the applicants' question papers through remote access from a chosen examination centre in Sonepat (Haryana).