PM Modi launches BJP's Delhi election campaign at Ramlila Maidan.

Amid the countrywide protests against the new citizenship law, Prime Minister Narendra Modi launched a fierce attack on his critics, challenging them to "lay bare" before the country if any of his policies discriminated between people. "Stand up and respect parliament, respect the government elected by the people," he exhorted them from Delhi's Ram Lila Maidan, against the backdrop of the majestic Red Fort.

At the outset of his address - meant to launch the party's election campaign - the Prime Minister set the tone with a new slogan. "Unity in diversity is India's specialty," he said.

Accusing his critics of being upset his return to power, he said, "I want to tell such people that if you dislike the mandate that I got then abuse Modi and go against Modi. But stop burning public property and destroying a poor man's auto".

Since the amended law was passed on December 11, protests have swept the country. The biggest of these was held on Thursday, when chaos ruled in 13 cities across India, with protesters defying the police and prohibitory orders banning large gatherings. A string of protests are being held today as well across Delhi, Bengaluru and Chennai.

The BJP has accused the opposition parties, especially the Congress, of engineering the protests. The Prime Minister, who on an earlier occasion said those protesting against the law can be "identified by their clothes", today ripped into the critics.

"I want to ask the liars -- that when we legalised the unauthorised colonies, did we ask them their religion or which party you support? Did we ask you for evidence of 1975 or 1980? Did we ask for any proof? The Centre's help was received by the Hindus, Muslims, Sikhs, Christians, everybody. Does is smell of discrimination anywhere? Then lay it out open before the nation."

The government, he said, had never asked for anyone's religion when it started the biggest health scheme in the country that helped 50 crore people with free treatment.

"Why is this conspiracy to shame India internationally going on? And I want to say if you don't like it, then abuse Modi and hate Modi... but don't burn people's property... and the stones they're throwing on police... when police does their duty, they came under attack," he added.

The Citizenship (Amendment) Act makes religion the test of citizenship in India for the first time. The government says it will help minorities from three Muslim-dominated countries to get citizenship if they fled to India because of religious persecution.

Critics say it is designed to discriminate against Muslims and violates the secular principles of the constitution.