Dozens of Indian opposition leaders were detained in New Delhi on Monday as they shouted slogans, jumped barricades and marched to the Election Commission in a rare public protest against what they say are electoral malpractices.

The credibility of elections has rarely been questioned in recent decades in the world's most populous democracy. Some analysts say the opposition accusations could damage Prime Minister Narendra Modi as he navigates one of the toughest periods of his 11 years in office.

Around 300 opposition leaders, including Rahul Gandhi of the main opposition Congress party, marched from parliament to the office of the independent election panel but were stopped by police some distance away.

The protesters shouted slogans against the panel and Modi's government, saying elections were being "stolen", and tried to push past barricades before being detained and taken away in buses.

"This fight is not political. This fight is to save the constitution," Gandhi told reporters. "We want a clean, pure voters' list."

Gandhi and Congress have alleged that voters' lists in states where the party lost are corrupted, with voters' names deleted or included more than once to rig elections in favour of Modi's Bharatiya Janata Party.

Opposition parties have also criticised the election panel's decision to revise the voters' list in the key northern state of Bihar just before state elections due later this year, saying it aims to disenfranchise large numbers of poor voters.

The BJP and the Election Commission have rejected the accusations.

'STATE OF BANKRUPTCY'

The commission has said that changes in voters' lists are shared with political parties and all complaints are investigated thoroughly. It has also said that voters' lists need to be revised to remove dead voters or those who have relocated to other parts of the country, among others.

Congress and its allies have fared poorly in two state elections that they had expected to win after an impressive show in last year's parliamentary vote, which saw BJP losing its outright majority and remaining in power only with the help of regional parties.

Congress has also complained about electronic voting machines and said the counting process is not fair, charges rejected by the election panel.

The BJP said opposition parties were trying to create a "state of anarchy" by sowing seeds of doubt about the electoral process.

"They are in a state of bankruptcy because of their continuous losses," federal minister Dharmendra Pradhan told reporters on Monday.