Delhi Chief Minister Arvind Kejriwal on Sunday asked if the Electronic Voting Machines (EVM) are prone to tampering, and said the incident in Madhya Pradesh pointed in that direction.The Election Commission of India (ECI) is set to replace over nine lakh EVMs with tamper-proof M3 EVMs before the next Lok Sabha elections in 2019."Does it mean that the present EVMs are tamper prone? That's v (very) scary. MP (Madhya Pradesh) incident shows that its software was altered," Kejriwal said in a tweet on Sunday.Soon after the results of Uttar Pradesh Assembly polls were declared, Bahujan Samaj Party chief Mayawati had alleged that the EVMs were tampered with.Other opposition parties, including the Congress and the Aam Aadmi Party (AAP), on Saturday sought a probe by the Election Commission after an EVM malfunctioned during an official demonstration ahead of the by-elections in Ater and Bandhavgarh assembly constituencies in Madhya Pradesh.The Congress wrote to the Election Commission urging it to revert to the system of paper ballot if political parties were not convinced about the credibility of the EVMs.Delhi Chief Minister Arvind Kejriwal also urged the ECI to investigate the cases of faulty EVMs to ascertain if they were tampered with to favour the Bharatiya Janata Party (BJP) in the just-concluded assembly elections in Manipur, Uttar Pradesh, Uttarakhand, and Goa.