Raising fresh doubts about the credibility of Electronic Voting Machines being used in ongoing parliamentary elections, leaders of 21 opposition parties have demanded the Election Commission to increase the number of EVMs which are randomly verified using Voter Verified Paper Audit Trail (VVPAT).

The leaders told a press conference in Delhi that 50 per cent EVMs should be verified against the VVPAT and they will move the Supreme Court again with their demand.

Andhra Pradesh Chief Minister and Telugu Desam Party Chief N Chandrababu Naidu said that they would prefer a complete return to the use of paper ballots, but they are seeking 50 percent VVPAT in the current elections considering shortage of time.

Naidu said the opposition parties were not satisfied with the April 8 Supreme Court order that directed the EC to increase the number of VVPAT count from one to five per constituency and a fresh petition will be filed in the matter or the parties will move a review plea.

Senior Congress leader Abhishek Manu Singhvi said that they will approach the Supreme Court and carry out a nationwide campaign on the issue of discrepancies in EVMs.

Referring to issues of malfunctioning of EVMs in the first phase of elections held on April 11, Singhvi said "questions were raised after the first phase of elections. We don't think the EC is paying adequate attention. If you press the button before XParty, vote goes to Y party. VVPAT displays only for 3 seconds, instead of 7 seconds."

"It has become even more necessary to count at least 50% of the paper trail of VVPAT, we will demand the same in the Supreme Court," Singhviadded.

Delhi Chief Minister and AamAadmi Party chief Arvind Kejriwal alleged people were losing faith in EVMs and want to return to paper ballots. But since there is paucity of time, at least 50 per cent VVPATs should be counted, he added.

The Bharatiya Janata Party spokesman G V L Narasimha Rao said the opposition party's objection to EVMs was an "act of self-deception and admission of defeat."

He said if EVMs were not trustworthy how did the Congress win assembly elections in three states Rajasthan, Chhattisgarh and Madhya Pradesh late last year. "It is a very convenient excuse to blame the EVM," Rao said.

Under VVPAT system, a hard copy is generated showing the name of the candidate and his or her election symbol and displayed on a screen for seven seconds before getting cut.

During the first phase of polling several cases of EVM malfunctioning were reported from Andhra Pradesh where TDP is fighting in all the 25 parliamentary constituencies as well as 175 assembly constituencies for which simultaneous polling was held.