Cambodia's government has hit out at Valentine's Day, warning students against losing the "dignity of themselves and their families" in a note sent to schools across the country.

Valentine's Day has become something of a favourite among young people in many Southeast Asian countries in recent years, with bunches of red roses and heart-shaped chocolates cropping up in stores and on street stalls each February.

But that has left some officials rattled, particularly in Cambodia and neighboring Thailand -- both of which have become renowned in recent years for issuing warnings about the pitfalls of young love and premarital sex ahead of the 14 February holiday.

The Cambodian Ministry of Education directive, which was sent to private and public schools on on Tuesday, ordered teachers to "take measures to prevent inappropriate activities on Valentine's Day".

The ministry said the increasingly popular holiday was driving young people "to overjoy, to forget about studying and to lose the reputation and dignity of themselves and their families".

"It is not a traditional event of our Khmer people," the statement said according to a copy seen by AFP.

Social conservatives in both countries see the day as a foreign import which represents a moral threat to traditional Buddhist beliefs.

Cambodian women in particular are under intense pressure to retain their virginity until marriage.

At the same time the country has become notorious in recent years as a regional hub for selling young women's virginity to wealthy men, something rights groups say underlines intense double standards over sexuality and gender. Last year officials in junta-run Thailand also sounded a note of caution over Valentine's day, calling on young people to have a special meal or visit temples instead of having sex. While both Cambodia and Thailand have a seemingly anything-goes image among holiday makers and thriving sex work industries, they also have a conservative streak. Health workers say sex education in both nations remains underfunded and of poor quality, partly because the subject of sex is so taboo. According to the United Nations, the birthrate among Thai teenagers was 47 per 1,000 girls from 2006 to 2010 -- roughly in line with neighbouring Cambodia, but significantly higher than Malaysia's 14. AFP