Aminul Haque Laskar, a Bharatiya Janata Party legislator from Assam, has received a letter asking him to resign within 15 days, the Hindustan Times reported on Tuesday quoting police officials.

Laskar, the BJP’s lone Muslim MLA in the state, received the handwritten letter on Saturday. Two bullets of a .32 pistol were taped to the letter, written in Bengali with red ink. “The letter was posted from Karimganj on May 22, and I received it on June 9,” Laskar said. “It accused me of siding with the BJP despite being a Muslim.”

The letter was purportedly sent by an organisation called Save Secure and Development Protection Force of Muslim, based in Barak Valley in South Assam, and signed by a person named Haidar Hussain Khan, who claims to be the vice-chairman of the group, reported Northeast Now.

“The letter also accused me of not opposing the Citizenship (Amendment) Bill, 2016 when the joint parliamentary committee came to Barak Valley for hearings in May,” said Laskar. He added that it could have been sent by “illegal business syndicates or land mafia groups” that have been affected by the state government’s policies.

Indrajit Chakraborty, the police officer in charge of the Silchar police station, said that an investigation has been launched to identify those responsible for sending the letter.

The Citizenship (Amendment) Bill aims to make crucial changes to the Citizenship Act of 1955. If passed, it would make undocumented immigrants – Hindu, Christian, Buddhist, Sikh, Jain and Parsi – from Afghanistan, Pakistan and Bangladesh eligible for Indian citizenship. It would also ease the terms of naturalisation for immigrants from these religious groups. However, several groups have objected to the proposed amendments.