Two leaders of India’s youth-led Cockroach Janta Party (CJP) were remanded in custody for five days on Wednesday, as police ratcheted up efforts to clamp down on anti-election commission protests.

CJP activists and opposition parties have defied a security crackdown to demand the resignation of India’s chief election commissioner, accusing the poll body of manipulating voter rolls to benefit Prime Minister Narendra Modi’s ruling party. The commission, which oversees voting in the world’s most populous nation, has denied any wrongdoing. Delhi Police said CJP leaders Ashutosh Ranka, 30, and Saurav Das, 27, were taken into custody for their “alleged repeated attempts to disturb public peace and violate the law”.

At the end of the five-day remand period, they could have their detention extended, be granted bail or be released.

On Tuesday, the pair jumped security barricades to wave the national flag at Jantar Mantar, a decades-old protest site that police have barred people from using.

“Their alleged attempts to instigate others through social media to engage in similar unlawful activities were also taken into consideration,” police added.

Parliamentary opposition leader Rahul Gandhi, from the Congress party, backed the men, who were detained after entering the site.

Jantar Mantar, in the heart of the capital, has been sealed off for days with yellow metal barricades and guarded by security personnel. Delhi Police said on Monday it had removed the site from its list of designated protest venues.

“Waving the Tricolour at Jantar Mantar in a peaceful protest is not a crime,” Gandhi said in a post on social media. “Jailing youth for it is an act of cowardice.”The Congress and CJP have both protested over the voter roll revision. Gandhi said on Wednesday that “all protests are one”. “Different banners, one cause,” he said.

CJP founder Abhijeet Dipke praised the men, saying they “knew they could be thrown behind bars” but went ahead to wave the national flag.

“They’ve shown the entire country that the only way to stand up to a bully like Modi is to never bow down, no matter the consequences,” he said in a post on social media.

Das has worked as a journalist, while Ranka, an engineer, studied at the prestigious Indian Institute of Technology and the London School of Economics.

Rights advocates and critics say Modi’s government has eroded democratic freedoms during more than a decade in power, citing pressure on journalists, civil society groups and political opponents – allegations the government rejects. Human Rights Watch said on Wednesday the Indian government must uphold the right of citizens to protest peacefully.

“The Modi government should stop throwing young protesters in jail and instead engage with them to address concerns over the right to vote and fairness of elections,” it said in a statement.

Journalists in New Delhi marched on Tuesday to protest the detention of reporters during demonstrations. The Press Club of India said attacks on journalists doing their jobs were “unacceptable”.

The electoral list revision, which began last year, has led to more than 133 million names being removed from electoral rolls, according to media reports. Critics say the exercise has disproportionately affected minorities, particularly Muslims. Election authorities say the move was intended to eliminate duplicate, deceased and fraudulent entries.

Members of Modi’s Hindu nationalist Bharatiya Janata Party have long alleged that large numbers of undocumented Muslim migrants from neighbouring Bangladesh have fraudulently entered India’s electoral rolls.

Home Minister Amit Shah, Modi’s powerful right-hand man, dismissed the protests as localised and accused Gandhi of pursuing an “action plan to protect infiltrators”.

“The people of India are not going to fall for your deception,” he said, predicting a “resounding majority” for government in the next general election, due in 2029.