ByGeeta Pandey and Nikita Yadav

BBC News, Delhi

Tens of thousands of people have gathered in Delhi for a major opposition rally demanding the resignation of India's chief election commissioner.

The rally, organised by the opposition INDIA bloc and led by Rahul Gandhi's Congress party, is taking place at Ramlila Maidan, a large ground in central Delhi known for hosting cultural events and political protests.

Visuals showed Gandhi in an open-top jeep alongside other opposition leaders heading towards the venue. The Gen Z-led pressure group Cockroach Janta Party (CJP) has also pledged support, though its leaders have yet to be seen.

Security has been tightened, with thousands of police and paramilitary personnel deployed near the grounds.

Sunday's event is the latest show of opposition anger over a voter-list revision exercise that has removed 130 million names from draft electoral rolls in India.

The Election Commission of India (ECI) says the exercise is aimed at updating the voters' list by purging names of people who have died or moved away from their registered addresses.

But opposition parties allege that the exercise - known as the Special Intensive Revision (SIR) - could benefit Prime Minister Narendra Modi's Bharatiya Janata Party (BJP) by removing eligible voters from the rolls. They accuse the Chief Election Commissioner (CEC) and the BJP of "vote chori (theft)". Both the BJP and the ECI have denied the allegations.

The controversy intensified in September when The Indian Express newspaper in its investigation, external reported that the CEC, Gyanesh Kumar, made key decisions related to the exercise without the agreement of the two other election commissioners, who had raised objections on more than a dozen occasions.

The Election Commission said differences of opinion were normal in any institution and did not affect its functioning.

But concerns over the revision process have continued, with the opposition parties, the CJP and student groups organising a number of protests in Delhi and other Indian cities.

On Saturday, leaders of the INDIA bloc staged a symbolic impeachment of Kumar at Congress president Mallikarjun Kharge's residence in Delhi. The INDIA bloc - short for Indian National Developmental Inclusive Alliance - is a group of opposition parties formed in 2023 to take on the governing BJP-led National Democratic Alliance.

The mock parliamentary session, presided over by former Lok Sabha Speaker Meira Kumar, saw leaders accuse the election chief of "conspiring to steal elections" and deliberately removing 130 million voters from electoral rolls.

Kharge, who is also the leader of the opposition in parliament's upper house, moved a symbolic motion seeking Kumar's removal, accusing him of undermining the electoral process and committing an act of "treason against the nation and the Constitution of India".

Several people whose names had been removed from electoral rolls during the revision exercise also attended the event.

The proceedings were purely symbolic and had no legal standing. Under Indian law, the chief election commissioner can only be removed through a formal parliamentary process.

Prime Minister Modi has not directly commented on the mock impeachment proceedings. However, speaking at a public rally on Friday, he said that "some people" wanted to create chaos across the country so that he could be defamed.

Later on Saturday, while addressing a separate rally, he also accused opposition parties of "abandoning their duty" and "tearing apart the dignity and boundaries of the constitution".

Last month, Congress MP and leader of the opposition Rahul Gandhi led tens of thousands of protesters in a march from Connaught Place in central Delhi to the Supreme Court, seeking the CEC's resignation.

"The march was just the trailer," a party leader told the BBC, adding that "Sunday's rally will be several times bigger than that".

Ahead of the rally, Gandhi said their protest was against "the demolition of Indian democracy", adding that "all the opposition parties and everybody who wants to come, political or non-political, is welcome".

"There is huge anger, huge emotional pain because millions are being disenfranchised," he said.

"We are all standing together because we are defending the Constitution. We are defending the idea of India. We are defending the vote, which is the expression of all Indians."

Delhi police have given permission to hold Sunday's rally, but it comes with several conditions. Media reports say the rally must end by 5pm, CCTV cameras must be installed at the venue and no marches will be allowed outside the designated protest site.

The planned mega rally has also divided opinion among traders in Chandni Chowk, one of Delhi's oldest and busiest markets, located less than a kilometre from Ramlila Maidan.

Earlier this week, a group of traders said the protest could hurt business during the festive season, coming just a week before Diwali.

But a rival group of traders said they supported Gandhi's rally and criticised the BJP for taking out a march through the market on Thursday, saying that disrupted the festive season more.

Authorities have deployed thousands of police and paramilitary personnel across the city, including the roads leading up to Ramlila Grounds, Sunday's protest venue.

The opposition, which has been preparing for the rally for days now, has accused the government of trying to stop people from travelling to Delhi to take part in the protest.

Rahul Gandhi has appealed to people to turn up in large numbers. "Don't worry about the police, don't worry about lathis [batons] - the BJP will not have the guts to try any of their antics," he wrote on X.

His comments come amid growing concerns about the policing of recent protests in the capital.

On 10 October, thousands of security personnel were deployed and large parts of the city were shut down to thwart protests called by the CJP against CEC Gyanesh Kumar.

All of the top CJP leaders were detained and many demonstrators were beaten and dragged through the streets to break up their protests. BBC reporters covering demonstrations saw, external police dragging away protesters and using batons on some of them.

The CJP has publicly backed the INDIA bloc rally, but it is unclear whether its senior leaders will attend.