The education ministry urged Leiyang city in Central China's Hunan province to properly solve the issue of "oversize classroom" which triggered an outcry of parents recently.

"Oversize classroom affects education quality and the healthy development of students mentally and physically while having potential safety hazard," Xu Mei, a spokeswoman of the ministry, said at a news conference on Thursday.

To slim the oversize classroom, more schools should be built and education resources should be allocated in a more balanced manner, she said.

Her remarks came after some parents of primary school students from Leiyang took to streets in protest of a relocation plan of the local education department.

Before the start of the autumn school semester, the Leiyang education department relocated 8,000 five- and six-graders of the city's public primary schools to other schools to meet the requirements of the central government to eliminate "oversized class" by the end of this year, according to Caixin.com.

Many parents of the children transferred to a branch school of the High School Attached to Hunan Normal University took to street on Sept 1 in protest against the air pollution in the newly decorated dormitories and the high fees of the school.

Some of the parents told Caixin that dormitory building of the school was still being renovated when their children went for registration, and the rooms emitted pungent smell of formaldehyde.

In addition, the privately run school charges 1,500 yuan a semester per student, compared with less than 200 yuan a semester charged by public schools.

The school has received more than 4,000 primary school students relocated from public schools.

Statistics show that about 40 percent of classes in primary schools and junior high schools in Leiyang have more than 56 students, which are called "oversized classes". And around 20 percent of the classes have more than 66 students, or "super-large classes".

According to a document issued by the State Council earlier this year, the super-large classes should be eliminated by the end of this year, and the other oversized-classes should be eliminated by the end of 2020.

The shortage of new schools is considered the reason behind the prevalent oversized classrooms of the city.

A report published by the ministry in 2014 said only one new school had been built in the central area of Leiyang from 2008 to 2014. Statistics show the city's population had more than tripled from 2001 to 2017.

The report shows Leiyang has not invested enough in education, and as more students from rural areas flocked to the central city to seek better education, the problem of oversized classrooms exacerbated.