NEW DELHI (Reuters) - Indian Prime Minister Narendra Modi contradicted his closest lieutenant over plans for a nationwide register as he tried to defuse protests against a citizenship law in which at least 21 people have been killed.

Modi’s Hindu-nationalist government says the Citizenship Amendment Act (CAA), which became law on Dec. 11, is needed to give persecuted non-Muslim minorities from Afghanistan, Bangladesh and Pakistan who fled to India before 2015 a pathway to citizenship.

But many Indians feel the law discriminates against Muslims and violates India’s secular constitution by making religion a test for citizenship. They say the law and a proposed National Register of Citizens (NRC) could be used to reduce Muslims to second-class citizens.

“I must assure Muslim citizens of India that this law will not change anything for them,” Modi said on Sunday at a rally in New Delhi, trying to stave off the biggest challenge to his leadership since he first swept to power in 2014. His government did not have a religious bias when introducing reforms, he added.

Modi also said that there had been no discussion on creating the nationwide register of citizens - directly contradicting key ally Home (Interior) Minister Amit Shah.

“Since my government has come to power, since 2014 to now, I want to tell (1.3 billion) citizens, there has been no discussion on even the word NRC,” Modi told a crowd of thousands.

But speaking in parliament last month, Shah told lawmakers unequivocally that the government would introduce a nationwide register.

In April, he laid out the chronology for the process, telling reporters: “First, there will be a Citizenship Amendment Bill ... after that, there will an NRC.”

In June, after Modi’s party was returned to power with a thumping majority, President Ram Nath Kovind also told parliament that the register would be on the government’s agenda.

Shah was appointed president of the ruling Bharatiya Janata Party (BJP) shortly after Modi’s election win in 2014, a post he still holds. Modi named him to the powerful home ministry after he was re-elected this year.

“Just who are you calling a LIAR, PM?” wrote The Telegraph newspaper in a front page headline on Monday. Below, it highlighted comments by all three, asking: “Who’s saying the truth?”

The prime minister’s office did not immediately respond to questions on the matter.

“HIGHLY UNLIKELY”

FILE PHOTO: India's Prime Minister Narendra Modi speaks to the media inside the parliament premises on the first day of the winter session in New Delhi, India, November 18, 2019. REUTERS/Altaf Hussain

Neelanjan Sircar, a professor at Ashoka University near New Delhi, said the ruling party was likely trying to confuse the issue with the electorate to beat back growing opposition.

“Is it credible that Amit Shah and Narendra Modi are not on the same page on something this important, on something that has taken up the headlines and caused protests the way it has? It just seems highly unlikely,” Sircar said.

In his speech on Sunday, Modi also blamed the Congress party and other opposition groups for spreading rumors that there were detention centers for illegal immigrants in India.

“It’s a lie, it’s a lie, it’s a lie,” the prime minister said.

In July, the government informed parliament about guidelines for detention centers, including construction of basic amenities like electricity, drinking water, accommodation and toilets with running water.

Reuters visited an under-construction detention center in India’s northeast in September.

So far, the citizens’ register has been restricted to the northeastern state of Assam, where it has been implemented under orders from the Supreme Court.

After officials vetted documents submitted by about 33 million people, 1.9 million people were excluded from the citizens’ list. Several hundred people unable to prove their citizenship are already in detention camps.

Many Indian Muslims see Assam as an example of what a nationwide exercise might mean for them, despite Modi’s insistence that there is no immediate plan for a nationwide register.

Mohammed Naeem, who joined a demonstration against the citizenship bill and the register in New Delhi hours after Modi’s speech on Sunday, said he was still fearful.

“The prime minister might say there is nothing to fear but do you see what is happening in Assam?” he said, walking amid protesters, joined by his wife and three young children.

“People are being forcefully evicted from their houses, detained.”