The education bureau of Xinzheng, Henan province, confirmed on Wednesday that a local teacher had died after teaching a class online.

The death of Liu Hanbo, a history teacher at Xinzheng No 3 High School, happened after she finished an online course at home on Friday, and local police have confirmed it was not a criminal case, according to a statement posted by the city's publicity department on microblogging platform Sina Weibo.

Expressing sadness about Liu's death, the education bureau said in a statement that she was modest, conscientious and responsible in her work, and that it has been trying to care and comfort her family.

The case aroused widespread public attention after Liu's daughter claimed that her mother died alone at home on Friday. She said her mother had suffered from online bullying after high schools citywide were required to teach classes online in the middle of last month.

It is not suggested that online bullying was a contributing factor in the death.

"I was told my mom's news two days after her death, because my dad, younger sister and I were all busy with study and work outside of the city," Liu's daughter said in her post on Sina Weibo.

She provided a video clip and said that a few internet users entered the online room and disturbed the order of the class by various means, such as by playing noisy music and being rude, while her mother livestreamed her class on Friday evening.

As of 7 pm on Wednesday, the daughter's post has been shared 180,000 times and the video clip has been viewed more than 2.54 million times. A topic tagged "Teacher of Xinzheng No 3 High School died after online course", for example, has also been read over 260 million times.

In response to the daughter's claim about the online bullying, the education bureau said in the statement that local police have filed a case to investigate, adding that the result will be open to the public in a timely manner.

"The internet isn't a lawless place, and we represent students and parents to call for relevant authorities to harshly crack down on behaviors involving online bullying," the bureau said.

"People who disturb social order, such as interrupting online classes, will be punished by police with fines or administrative detention," said Xu Hao, a Beijing lawyer. "If their behaviors are serious enough, they may even face a sentence of up to five years in prison under the Criminal Law.

"How and why Liu's online room number and password were known by the troublemakers needs further police investigation," he said.

"If the class information is found to have been released by those under the age of 18, the punishment will be relatively lenient, and if the leakers are under the age of 14, they will be exempted from punishment, but their guardians will be ordered to strengthen management and education for the children," he added.