The Election Commission denied on Monday that voting machines in by-elections failed on “large scale” after opposition parties in Uttar Pradesh said voters were cheated and the Bharatiya Janata Party candidate in Maharashtra’s Palghar Lok Sabha seat complained of glitches.

Tabassum Hasan, who is contesting the Kairana Lok Sabha by-election in Uttar Pradesh on a Rashtriya Lok Dal ticket and is supported by four other Opposition parties, wrote a letter to the Election Commission and alleged there were “continuous complaints” of electronic voting machines (EVM) and Voter Verifiable Paper Audit Trail (VVPAT) machines not working in most polling booths.

“Voters are being denied their rights but nobody is listening to our complaints,” said Hasan, who listed booths where EVM or VVPAT allegedly failed to work.

Samajwadi Party president Akhilesh Yadav said on Twitter people should go out and vote despite complaints of EVMs not working in “several places” in Kairana and the Noorpur assembly seat.

Samajwadi Party spokesman Rajendra Chaudhary said 140 EVMs were tampered with in Noorpur and that similar reports have come in from Kairana. “The BJP wants to avenge their defeat in the earlier bypolls in Gorakhpur and Phoolpur anyhow and win the ongoing polls,” he said, referring to the Bharatiya Janata Party.

BJP’s in-charge of Kairana election Devendra Singh said he was also surprised by malfunctioning EVMs. “The allegation of opposition parties that BJP is tampering EVMs is baseless. It seems to be a technical problem,” said Singh.

He claimed that EVMs at over a hundred booths in areas dominated by BJP supporters were also found faulty.

“The party has lodged a complaint with the Election Commission of India as well as the state election commission,” Singh said.

The Election Commission said replacing defective EVMs and VVPATs is “normal” and it doesn’t “vitiate the integrity or credibility of the poll process”.

“News reports surfacing in the media alleging ‘large scale’ failure of EVMs and VVPATs in the ongoing by-elections and interruption of poll in the States of Maharashtra and Uttar Pradesh are an exaggerated projection of reality,” said the Commission in a press statement.

Technical problems were reported with 35 EVMs and 98 VVPAT machines during Lok Sabha bypolls in Maharashtra’s Palghar and Bhandara Gondia constituencies. Rajendra Gavit, BJP candidate in Palghar, demanded that the polling time be extended because of EVMs and Nationalist Congress Party leader Praful Patel alleged that almost 25% of the machines had malfunctioned in Bhandara-Gondia.

However, the Commission said voting had not been cancelled in any place in Maharashtra because of the glitches.

VVPAT is an independent verification system that allows people to check if their vote has been cast correctly from voting machines.

Opposition parties, after the BJP came to power in 2014, have often alleged that EVMs can be rigged and urged the Election Commission to return to paper ballots. The Commission has rejected their suspicion and in April 2017 announced an “open challenge” to hack the machines.

Polling is underway for four Lok Sabha and ten assembly by-elections across the country, the results of which could control the tone and tenor for the 2019 general elections for the BJP and the opposition.