The police are yet to identify and arrest anyone involved in issuing a death threat to the principal of Dhaka Ramakrishna Mission.

“We have deployed teams at Kishoreganj, Gazipur, Wari, Uttara and other parts of the country, which are mentioned as temporary addresses of the so-called sender AB Siddique,” said Zeahad Hossain, officer-in-charge of Wari Police Station.

Apart from police, members of other law-enforcement agencies have also been working on the issue.

Meanwhile, the RK mission in Belur Math of Kolkata said the mission's followers in India saw with relief Bangladeshis expressing shock and condemning the death threat.

“The people of Bangladesh are the protectors of the mission. They have protected it till date and we believe they will protect it in the future,” said Shubhakar Ananda, a spokesperson of the RK Mission in Belur Math. 

Security has been beefed up at the mission in the capital's Gopibagh, said Syed Nurul Islam, deputy commissioner (Wari division) of Dhaka Metropolitan Police.

The Indian High Commission in Dhaka took up the issue with Bangladesh's foreign ministry and police, said Vikas Swarup, spokesperson of the Indian external affairs ministry, on Friday.

India's response to the threat was largely due to the intervention of the Indian Prime Minister's Office as PM Narendra Modi is a follower of RK Mission, reports our New Delhi correspondent. The RK Mission in Dhaka was one of the few non-government institutions that Modi visited during his two-day Bangladesh tour in June last year.

Sources said the Indian PMO had instructed its Ministry of External Affairs to take the threat issue seriously and act.

Swami Suhitananda, general secretary of the RK Mission headquarters, met senior officials at the Indian PMO on Friday and discussed the threat issued to the mission's branch in Bangladesh, said mission sources.

A police official in Dhaka on Thursday said the priest received the letter on a IS letterhead, with the perpetrator identifying himself as one AB Siddiqui.

“Bangladesh is an Islamic state. You can't preach your religion here. If you continue preaching, you'll be hacked to death with machetes between the 20th and 30th,” the officer quoted the letter as saying.

The development comes at a time when suspected militants have killed a number of secular activists, Hindus and other religious minorities across Bangladesh in recent months.