Hardline Hindu groups in India have threatened to take action against young couples who make public shows of affection on Valentine's Day.
Some Hindu groups say India is sinking under western values
The occasion of 14 February has become increasingly popular among young people in many Indian cities and towns.
Shops do brisk business selling heart-shaped balloons, chocolates, cards and flowers.
One Hindu group, the Shiv Sena, said its volunteers would photograph couples caught in "compromising positions".
Overt signs of affection, such as kissing and holding hands, are frowned upon in much of traditional Indian society.
Shiv Sena has warned that its activists will stake out public parks, cinemas and shopping malls in a number of cities, and photographs of couples courting will be handed over to their parents.
Mahaveer Parikh, a spokesman for another hardline group, Bajrang Dal, told the BBC from Jaipur: "We will protest with all our might. We will do anything it takes to stop young couples in a behaviour that is against Indian culture.
"Even exchanging cards at a young age is against Indian culture because it pollutes young minds."
But a students' organisation affiliated to the ruling Congress party - the National Students Union of India - has threatened to retaliate if Hindu activists "harass" young couples on Valentine's Day.