Bal Thackeray, a powerful politician who heads the Hindu nationalist Shiv Sena party, the ruling coalition's third largest member, asked activists to stage demonstrations outside bars, clubs and colleges that plan to organize celebrations on Valentine's Day.
``What is this Valentine's Day and who brought this Western craze here, which is alien to our culture?'' Thackeray said in Monday's edition of Saamna, or Confrontation, a newspaper published by his party.
He warned that party members would hold protests if any ``indecent'' activities were held on Valentine's Day, which is Wednesday.
The party objects to the exchange of Valentine's Day cards and gifts, and feels that the annual festivities to celebrate love are indecent.
But in Bombay, India's financial and film capital, and in other large cities, dating is common and is increasingly gaining social acceptance.
Bombay mayor Hareshwar Patil, also a Shiv Sena member, said he supported Thackeray's stance and called for a ban on all celebrations of Valentine's Day.
``If any such indecent celebrations are held, they will not be allowed,'' said Patil.
He said such imitation of the West ``spoils our young boys and girls.'' But he said there was no formal ban issued by the civic administration on the celebrations.
Thackeray blamed multinational companies for promoting Valentine's Day in India, saying it was a conspiracy to sell their products to Indians.
"We should focus on good work, good thoughts, love and harmony in our society, and not let such Western culture spoil us," he added.
Several other Hindu hardline groups have already begun an assault on Valentine's Day this year.
Members of the Bajrang Dal and Hindu Jagran Manch groups destroyed several shops selling Valentine's Day cards in the northern Indian city of Kanpur in Uttar Pradesh state, said the Indian Express newspaper.
"We had announced in advance that the sale of Valentine's Day cards will not be allowed. Now the violators will have to have the consequences," Arvind Singh, of Bajrang Dal Kanpur, was quoted as saying by the paper.
Valentine's Day was almost unknown in India until the last few years, but it has now become popular in big cities much to the chagrin of more conservative elements of Indian society.
Hindu radicals regularly disrupt cultural events, films or even cricket matches that are deemend to be contrary to Indian values.
Last year Hindu hardliners in Uttar Prasesh passed a dress code for school girls asking them to wear traditional Indian clothes instead of the Western dress of skirt and blouse.