India, June 3 -- The Centre on Tuesday replaced the chair and the secretary of the Central Board of Secondary Education (CBSE) and started a probe into the procurement of services for the board's controversial, glitch-prone onscreen marking (OSM) system amid allegations of irregularities in the full-scale rollout of the platform that was used to assess Class 12 answer scripts.

The moves came after the intervention of Prime Minister Narendra Modi, people familiar with the development said.

CBSE chairman Rahul Singh and secretary Himanshu Gupta were transferred and were replaced by senior bureaucrats Prashant Lokhande and Varun Bhardwaj respectively, the government said in separate notifications.

Concurrently, through a Cabinet Secretari...