Former Indian Prime Minister Manmohan Singh Friday expressed concern over rising religious intolerance in his country after a spate of attacks against Muslims, leftwing activists and minority people.

In a function marking the 125th birth anniversary of former Indian Prime Minister Jawaharlal Nehru, Singh said the country is deeply concerned at the "blatant violation" of right to freedom of thought, belief and speech and termed such incidents as an "assault to nation" by extremists.

"The assault or murder of thinkers for their disagreement in views cannot be justified on any ground. All right thinking people have condemned such incidents in strongest term. It is an assault to nation," he said.

Describing the assault on Muslims and leftwing activists by extremists as "an attack on the nationhood," the former prime minister said everybody "in their right mind" has condemned with the strongest terms such actions.

Extremists have recently staged murder and attacks upon Muslims and leftwing activists, killing at least four of them.

Many intellectuals, artists and scholars have criticized the government of Bharatiya Janata Party for keeping silent over the incidents. The opposition Congress and leftwing parties have also staged protests over the incidents.