The Central Bureau of Investigation (CBI) on February 25 arrested Anand Subramanian, a former top official of the National Stock Exchange (NSE), in connection with alleged favour dolled out to certain traders.

The development comes as authorities pressed ahead with an investigation into whether high-frequency traders were given unfair access to network servers at the exchange.

News reports suggest that Subramanian, the former group operating officer and advisor to former managing director Chitra Ramkrishna, was held late on Thursday night from Chennai.

Subramanian was the chief strategic advisor from April 1, 2013 before he was re-designated from April 1, 2015 until October 21, 2016.

The CBI has also started interrogating Chitra Ramkrishna, Anand Subramanian and Ravi Narain.

All these were questioned in Mumbai and Delhi in connection with new facts that had emerged in the 2018 NSE scam case where certain private individuals, and unknown NSE and SEBI officials were accused of preferential access to NSE's server architecture and misuse of colocation facility.

CBI had recently also visited the Securities and Exchange Board of India (SEBI) office and collected documents.