A 28-year-old Taiwanese university lecturer had hearts racing after a photo of her standing in a black mini-dress at the front of her class went viral.

Axar.az reports citing foreign media.

A South African teacher has unwittingly thrown down a challenge for the unwanted title of "world's sexiest teacher" after images of her hit social media.

Lulu Menziwa, 26, teaches English in East London, a city in Kwa Zulu Natal, and until now her ample charms had been a well-kept secret.

But Twitter user Lufuno Mathoni posted pictures of her last week and jokingly told an education department chief to take pity on boys in the class, who were struggling to concentrate.

"You're making it hard for our kids to pass," he tweeted, although he has since removed the tweet.

South African newspapers picked up the story and soon Miss Menziwa's stunning figure had gone viral.

It comes only days after Cheng Jhia-wen was dubbed "Taiwan's hottest teacher" after she gained 100,000 followers on Instagram overnight.

In a live video on Instagram Miss Menziwa said she was flattered but just wanted to concentrate on teaching.

​"Please stop it…I don't like it any more," she pleaded in a video, which has since been parodied on social media.

She has since deleted her social media accounts.