India, Aug. 19 -- The Union education ministry on Tuesday said the National Testing Agency (NTA) has removed 600 subject experts, is rolling out a four-tier question-paper checking system and will shift its headquarters from Okhla in south Delhi to central Delhi, as the testing body embarks on a sweeping overhaul following a series of paper leaks and question-paper errors that hit high-stakes examinations over the past two years and affected millions of students.

The measures were disclosed a day after the ministry directed NTA to "fix accountability", conduct a thorough audit of its examination processes and submit a report on corrective action within 30 days.

Union education minister Pralhad Joshi held meetings with NTA director gener...