As lovers in Thailand prepare to shower each other with tokens of affection this Valentine's Day, health authorities are urging couples to practice safe pandemic sex -- including wearing masks during intercourse.

Daily coronavirus case numbers in the Southeast Asian tourism hub have climbed from about 8,000 at the start of the month to almost double in the past fortnight.

Health authorities have expressed concerns this February 14 could exacerbate the trend, while acknowledging people have sex on other days too.

"Covid isn't a sexually transmitted disease, but catching Covid is possible through close-contact breathing and exchanging saliva," Bureau of Reproductive Health director Bunyarit Sukrat told AFP on Friday.

He recommended couples perform antigen tests before their date night to prevent passing on the virus to their partner.

Lovers are urged to "avoid face-to-face sex positions and deep kissing" and use contraceptives if they wish to avert unwanted pregnancies, he said.

"If possible, wearing face masks while having sex can help reduce Covid risks," Bunyarit said.

The holiday is popular across the kingdom and considered an auspicious day for couples to tie the knot.

There are often long queues at marriage registration offices, especially in the Bangkok district of Bang Rak, which translates to "love district" in the Thai language.