A key terror suspect believed to have been involved in a plot to assassinate Bangladesh Prime Minister Sheikh Hasina has been arrested.

Shahnor Alom, who was on the run in India, was detained in a village in the northeastern state of Assam on Friday.

A senior intelligence officer told Reuters that Alom is an operative of a banned Bangladeshi group active in eastern India.

"Based on specific intelligence, he was caught last night hiding in his relative's house in a village in Nalbari district," the officer said.

Indian security officials said they uncovered a plot against Hasina in October, after two members of the Jamaat-ul-Mujahideen Bangladesh group were killed in an explosion while building homemade bombs in Burdwan, West Bengal, which borders Bangladesh.

A third individual was critically injured in the blast. Officers subsequently uncovered extremist documents and manuals used for making bombs at the site.

Indian authorities fear that threat levels are rising in India due to a combination of local and regional factors, including the election of a controversial right-wing prime minister in India; the withdrawal of western troops from Afghanistan; worsening relations between India and Pakistan, and the rise of the Islamic State.

There have been long-standing fears of the risk of terrorism from Pakistan. The attackers responsible for the deadly assault on Mumbai in 2008 were from the Pakistan-based Lashkar-e-Toiba organisation. However, Indian authorities have only recently become concerned about Bangladesh.

With a population of around 150m people, Bangladesh is one of the world's largest predominantly Muslim countries. It has suffered three major army coups and around two dozen smaller rebellions since gaining independence from Pakistan in 1971.

In November, Kolkata-based warships were moved offshore after officials received intelligence about a potential attack similar to an assault launched by the new al-Qaida in South Asia group in Karachi earlier this year.