The Central Bureau of Investigation on Thursday conducted searches on the premises of former Union Finance Secretary Arvind Mayaram in Delhi and Jaipur in connection with a corruption case, PTI reported.

The CBI had booked Mayaram and other unknown officials of the finance ministry on January 10 for allegedly extending undue favours to a United Kingdom-based company for supplying an exclusive colour shift security thread, reported The New Indian Express. The security thread is used to detect counterfeiting in currency notes.

Mayaram was booked under sections of the Indian Penal Code pertaining to criminal conspiracy and cheating as well as provisions of the Prevention of Corruption Act.

The central agency conducted searches weeks after Mayaram joined the Congress’ Bharat Jodo Yatra in Rajasthan. The Congress has claimed that the march is aimed at countering the politics of hatred espoused by the Bharatiya Janata Party.

The CBI alleged that Mayaram, as the finance secretary, had illegally extended an expired contract with De La Rue International Limited for the supply of the exclusive colour shift security thread. The agency claimed that the official did not take the mandatory security clearance from the home ministry and also did not inform the finance minister about the extension.

This was the fourth extension granted to De La Rue International, according to the FIR.

The Reserve Bank of India had first signed an agreement with the firm on September 4, 2004, The Hindu reported. At the time, the company claimed that it had exclusive manufacturing rights for the security thread, according to the CBI.

However, citing a Reserve Bank of India report, the central agency said that De La Rue International did not have a patent for the colour shift thread at the time. The Security Printing and Minting Corporation of India had reportedly submitted a similar report in 2007.

The patent was reportedly granted on June 17, 2011.

The CBI said that the illegal extension of the contract with De La Rue International led to wrongful gains for the company as well as loss to the exchequer.