LUCKNOW, India (AP) - Shopkeepers in India's largest state closed their shutters Tuesday after a right-wing Hindu organization threatened to attack shops selling Valentine's Day cards and gifts.

Police guarded the main market in Lucknow, capital of Uttar Pradesh state, to prevent confrontations between Hindu nationalist activists and people trying to buy Valentine's Day cards. Valentine's Day is a celebration of romantic love.

A group called the Hindu Jagran Manch, or the Hindu Awakening Platform, said Valentine's Day was an affront to Indian traditional culture and warned against Feb. 14 celebrations in the city. Many conservative segments of Indian society view the day as indecent.

``Valentine's Day, Mother's Day and Father's Day ... these are all the gimmicks of multinational companies to market their products. Valentine's Day is against the culture and ethics of Indian society,'' said Vinay Tewari, a Manch leader.

``We will stop them physically and will not allow them to organize any event in this regard,'' he said.

Fearing violence, some high school and university students stayed away from businesses in Lucknow. Many were upset.

``Nobody can play the role of cultural police. No political or social organization has the right to interfere in our personal freedom,'' said Alok Singh, a Lucknow University student.

Shopkeepers said they decided to close after Hindu Jagran Manch activists on Monday attacked shops selling Valentine's Day cards in Kanpur city, 40 miles southwest of Lucknow.

In Bombay, right-wing Shiv Sena party chief Bal Thackeray on Monday asked activists to demonstrate outside pubs and clubs that planned to celebrate Valentine's Day.

Jai Bhagwan Goel, the Shiv Sena's northern India chief, was quoted by a newspaper in New Delhi as saying the Sena would explain to people his party's objections to Valentine's Day. But he said the party would resort to violence if its objections were ignored.

``We will explain to people with folded hands. But if they resist, we can also break arms,'' The Statesman newspaper quoted Goel as saying Tuesday.