Police in the eastern Indian state of West Bengal are investigating the gang-rape of a 71-year-old nun.

Five people have been detained for questioning but arrests are yet to be made.

Prayers were said for the nun at churches across the country on Sunday.

"In our Sunday Mass, we prayed for the sister to recover quickly from trauma, fear and her physical injuries. We will pray for her again this evening," Thomas D'Souza, the archbishop of Kolkata, told AFP news agency.

The nun was attacked late on Friday after a gang of at least six robbers broke into a Christian missionary school in Nadia district, police said.

The men gagged a security guest before assaulting the nun.

The gang then vandalised the chapel of the Convent of Jesus and Mary School before escaping with money, a laptop and a mobile phone.

Local residents of Nadia, including students of the nun's school, took to the streets in protest on Saturday, blocking roads and a rail track.

The nun has been admitted to hospital where she is recovering, Anuj Sharma, a West Bengal police inspector-general, told AFP.

"Two people have so far been arrested," he said.

'Horrific crime'

Mamata Banerjee, West Bengal's chief minister, condemned the incident in a statement and has ordered an inquiry by the Criminal Investigation Department (CID).

“CID will be examining all aspects to this horrific crime. Swift, strongest action to be taken," she said.

Listening Post: India's rape debate

Four of the six attackers have been identified through CCTV footage and authorities are offering an award of about $1,500 for any leads on the suspects.

Arnab Ghosh, a police superintendent who visited the convent, told AFP that the robbery appeared to have been planned.

"CCTV footage showed that six men, aged between 20 and 30, scaled the boundary wall around 11.40 pm and entered the school and disconnected the telephone lines," he said.

The attack comes at a time of intensified debate and heightened sensitivity over sexual violence and women’s safety in India.

Last week, the Indian government banned a documentary about the 2012 gang-rape of a Delhi physiotherapy student which caused national outrage and led to a significant reform of India's rape laws, although many campaigners say little has changed on the ground.

Authorities said screening the documentary could have caused public disorder, but critics accused the government of being more concerned with the country's reputation than the safety of its women.

Over a week ago, a mob in the northeastern state of Nagaland dragged a suspected rapist from a prison and lynched him. 

Source: Agencies