New Delhi, October 6: The Election Commission's Special Intensive Revision of voter rolls is at the centre of India's biggest political row. Here is what it is.

The SIR is an exercise to check and clean voter lists. It aims to remove duplicate, shifted and deceased entries and add eligible new voters.

The Election Commission says the revision protects the integrity of elections. It says differences of opinion inside the poll body are normal and all actions were lawful.

The opposition alleges the exercise risks excluding genuine voters, especially poor and marginalised people who may lack documents. It claims the revised lists benefit the BJP. The BJP denies this.

The row grew after reports that two election commissioners had questioned the process. The opposition also alleges Form 6, the voter registration form, was changed without proper authority.

The Supreme Court on Monday agreed to hear petitions on the issue. It said it would annul any poll-body orders not in keeping with the law.