India's national song Vande Mataram has found itself in the thick of a political controversy.
Bankim Chandra Chattopadhyay wrote Vande Mataram
The Hindu-nationalist Bharatiya Janata Party wants the song to be sung in all schools on 7 September, the centenary of its adoption.
Muslim groups say the Sanskrit-language song is a hymn to the Hindu goddess Durga and it is against the tenets of Islam to sing it.
The song was written by the Bengali Bankim Chandra Chattopadhyay in 1876.
It was first sung at the Congress Party session in Varanasi in 1905.
Vande Mataram which translates as "Mother, I bow to thee" or as "Hail to the mother" became the rallying cry for Indians fighting British colonial rule.
After the country's independence in 1947, the song was the front-runner in the race for India's national anthem, but it lost out to Nobel laureate Rabindranath Tagore's more secular Jana Gana Mana following opposition from Muslim groups.
But Vande Mataram is still regarded highly and the song is played in Parliament at the beginning and end of each session.
Earlier this month the Congress Party-led federal government asked all schools, including Islamic madrassas, to get students to sing the song on its centenary.
After Muslim leaders objected, the government backed down and made singing voluntary.
'Symbol of national pride'
But the Hindu nationalist BJP has now joined the fray - it says the government's climb-down encourages a lack of patriotism.
AR Rahman's album became hugely popular
The party has said it will be mandatory for all educational establishments in the five states which it rules to sing Vande Mataram and has threatened action against those who disobey the order.
"There are some things which are symbols of national pride and Vande Mataram is one of them. It can't be made optional," the Reuters news agency quotes senior BJP leader, Vijay Kumar Malhotra, as saying.
Some Muslim groups say the song cannot be a yardstick for measuring patriotism. They say they will not sing it as "it is against their religion to pray and bow before anyone except the Almighty".
Some Muslim groups have threatened that they will go to the court against the order.
However, the song has found support from many Muslims in India.
A few years ago, well-known composer AR Rahman set the song to modern music and the album became hugely popular with the public.