The definitive list is to be finalised in December.
A retired Indian Army officer was among more than 40 lakh people left out of Assam's final draft National Register of Citizens (NRC) which was made public on Monday, deepening concerns over an allegedly faulty process to weed out illegal migrants.
Alleging vote and divisive politics by the Bharatiya Janata Party (BJP), Mamata said, "For how long will you keep lynching, play divide policy?"
According to the census, Assam's population rose by 50% between 1970 and 1979, a rise that has mainly come from the Bengali-speaking Muslim population across the border. One name missing from the list was Mohd Azmal Hoque, a retired soldier from Assam who had served in the military for 30 years and retired on September 30, 2016.
Resource-rich Assam, which borders Muslim-majority Bangladesh, is in the grip of social and communal tension as residents campaign against illegal immigrants, a fight backed by Prime Minister Narendra Modi's Hindu nationalist-led government.
Assam has witnessed prolonged protests against so-called foreigners, which includes both Hindus and Muslims.
The citizenship test is the culmination of years of often violent agitations by Assamese demanding the removal of outsiders they accuse of taking jobs and cornering resources in the state of 33 million, known for its tea estates and oil fields. Hundreds of thousands of people fled what was then East Pakistan in the 1970s, most settling in Assam.
The NRC is an application-based process and if someone does not apply for inclusion of name, that person's name will not figure in the list, however prominent the individual may be, the official said.
"No genuine Indian citizens need to worry as there will be ample opportunities given to them to enlist their names in the final NRC", he told a news conference in Assam's biggest city Guwahati. "We will provide assistance to them to file claims and objections". "So, there is no reason to fear".
Asked whether West Bengal would give shelter to those whose names have not appeared in the final NRC draft, she said, "They have their homes ... they are inhabitants of Assam".
Asking the opposition to list out what role the government has played in the NRC, Singh said, "It is a sensitive issue and should not be politicised unnecessarily".
"If the government has chose to brand us foreigners what can we do?" said Abdul Suban, 60, a Bengali-speaking Muslim, earlier.