NEW DELHI , May 21 : Former President Pranab Mukherjee today expressed concern at allegations of EVM or vote machine tampering - described by him as tampering of voters' verdict -- and said the "onus of ensuring institutional integrity" lies with the Election Commission. "The safety and security of EVMs which are in the custody of the EC is the responsibility of the Commission," Pranab Mukherjee said in a statement.

A series of video clips have surfaced, which, opposition parties say, prove that EVMs (Electronic Voting Machines) are being tampered with or being transported in private cars in parts of Uttar Pradesh, Bihar, Punjab and Haryana.

"There can be no room for speculation that challenge the very basis of our democracy. People's mandate is sacrosanct and has to be above any iota of reasonable doubt," said the former president. "A firm believer in our institutions, it is my considered opinion that it is the 'workmen' who decide how the institutional 'tools' perform," he added.