More than halfway through India's six-week national elections, the world's biggest, the Congress party-led opposition complained in a letter to the Election Commission of India on Friday that "no meaningful action has been taken to penalize those who are guilty in the ruling regime".

This was a "complete abdication" of the commission's duty, it said. "As a result there has been an unchecked and brazen continuation of these violations, which are now committed with impunity and utter disregard."

The watchdog is responsible for ensuring political parties do not violate election rules against promoting division along religious, caste or linguistic lines in the multiethnic South Asian nation.

In his campaign speeches, Modi, seeking a rare third consecutive term, has targeted the Congress, claiming it wants to help minority Muslims at the expense of other socially disadvantaged groups.

Representatives for the commission and Modi's Hindu-nationalist Bharatiya Janata Party (BJP) did not respond to requests seeking comment.

Election results in the world's most populous nation are to be announced on June 4.

The commission on Tuesday ordered social media platform X to take down a video posted by a BJP state unit that accused Congress leaders of planning to extend welfare benefits to Muslims at the cost of other disadvantaged tribal and Hindu caste groups.

While not making any rulings on the complaints, the commission has sought a response from BJP chief J.P. Nadda for an April 21 speech in which Modi said the Congress planned to redistribute wealth from Hindus among Muslims, whom he called "infiltrators" and "those with many children".

The commission has also sent a notice to the Congress regarding complaints by the BJP, which says it has filed three complaints.

"The delay puts a question mark on the credibility of the election commission and therefore on the election process," said S.Y. Qureshi, a former head of the three-member election commission. "Any damage to its reputation will cause incalculable harm to the legitimacy of India's democracy."

The opposition letter mentions 10 complaints the Congress had lodged since April 6 against Modi and key aides for what it calls "divisive", "false" and "provocative" statements that sow sectarian division and misrepresent Congress' positions.

"We are not told what is the response, what is the action being taken," Congress lawmaker Abhishek Manu Singhvi told reporters after meeting commission officials on Friday.

"This is an irreversible window," Singhvi said. "If they don't act promptly it would be a complete abdication of constitutional duty."

Ashok Lavasa, who was an election commissioner during the 2019 general election, said the process from receiving a complaint to deciding on it "should not take more than three to four days because otherwise it loses purpose", as the campaign phase is quite short.