New Delhi: India has stepped up security along its largely porous eastern border with Bangladesh and is using "chilli and stun grenades" to block the entry of Rohingya Muslims fleeing from violence in their homeland of Myanmar, officials said on Friday.

Border forces in Hindu-majority India, which wants to deport around 40,000 Rohingya already living in the country, citing security risks, have been authorised to use "rude and crude" methods to stop any infiltration attempts.

"We don't want to cause any serious injury or arrest them, but we won't tolerate Rohingya on Indian soil," said a senior official with the Border Security Force (BSF) in New Delhi.

"We're using grenades containing chilli spray to stop hundreds of Rohingyas trying to enter India ... the situation is tense," added the official, who declined to be identified as he was not authorised to speak to media.

More than 420,000 Rohingya have fled to Bangladesh since Aug. 25, when a coordinated attack by Rohingya insurgents on Myanmar security forces triggered a counteroffensive, killing at least 400 people, mainly militants. The United Nations has called the assault a "textbook example of ethnic cleansing".

Densely populated Bangladesh is struggling to shelter all the refugees desperate for space to set up shacks, sparking worries in India that the influx could spill into its territory.

R.P.S. Jaswal, a deputy inspector general of the BSF patrolling a large part of the border in India's eastern state of West Bengal, said his troops were told to use both chilli grenades and stun grenades to push back the Rohingya.

A chilli grenade makes use of a naturally-occurring compound in chilli powder to cause severe irritation and temporarily immobilise its target.

Prime Minister Narendra Modi's Hindu nationalist government is growing increasingly hostile towards the Rohingya in India, with Home Minister Rajnath Singh calling on Thursday for their deportation as illegal migrants.

Seeking to get legal clearance for the deportation plan, the home ministry told the Supreme Court this week it would confidentially provide it with intelligence information showing Rohingya links with Pakistan-based militants.

Most of the peaceloving refugees had no link to criminal activity, two Rohingya men protesting against the deportation move told India's top court on Friday.

An official of India's federal investigations agency said it was seeking help from Muslim religious leaders to step up surveillance of the Rohingya.

Police have arrested a suspected al Qaeda member they believe was trying to recruit Rohingya in the country to fight security forces in Myanmar. More than 270 Rohingya have been in Indian jails since 2014.

"Our investigations have revealed that Al Qaeda wants to use India and Bangladesh as their base to start a religious war against Myanmar," said New Delhi police official Pramod Singh Khuswah. "Clearly they are a threat to our security."