A primary school teacher in Yunnan province has been arrested over allegations he raped five girls.

Authorities in Shuangjiang county confirmed on Tuesday that the suspect Yang Shaochun is in custody and being investigated.

No more details of the teacher or victims have been released.

News of the arrest broke on Sina Weibo, China's Twitter-like service, when a blogger using the name Gusong XXX wrote that five girls at Tonghua Primary School had been raped by a teacher at the school.

The arrest comes amid a series of investigations into alleged child sex abuse nationwide, including one case in Hainan province in which a school principal and government employee were convicted last week and sentenced to 10 years in prison for sexually assaulting girls.

On Monday, a court in Qianshan county, Anhui province, sentenced principal Yang Qifa, 59, to 18 years in prison for the rape and sexual assault of nine girls.

With sex abuse in the spotlight, child protection experts say more surveillance is needed to monitor teachers' behavior.

Zhang Yun, a professor at Yunnan Normal University's School of Educational Sciences and Management, said more legal training should be given to increase teachers' awareness, especially in western regions such as Yunnan, Gansu and Guizhou provinces.

"Parents must educate children and tell them to shout out for help when someone tries to touch them," he said.

Li Qiang, a professor of sociology at Tsinghua University, said most school sex abuse cases happen in small rural towns or villages.

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"Awareness of sex is low in rural areas and students usually believe teachers will always be good to them," he said.

"Unfortunately, some teachers take advantage of the innocence of girls."

A 2008 report by the Beijing Youth Legal Aid and Research Center said a high percentage of sexual abuse occurred at rural schools - about 60 percent.

Rapes committed by principals or teachers accounted for more than 70 percent of the total, the report said.

Zhang cited a report by People's Public Security University of China that said only one-seventh of school rapes nationwide are exposed by the media, with other cases going unreported.

"Parents are reluctant to let neighbors know about the 'shameful fact' their daughters were raped," he said.

Tong Lihua, director of the Beijing Youth Legal Aid and Research Center, said: "Sex education must be strengthened at school, especially in rural schools. Teachers must also be severely warned before any bad behavior occurs."

In Zhejiang province, schools will no longer offer permanent jobs for teachers, who will be assessed and registered every five years.

Any teachers who commit "moral violations" and cause "negative social impact" will have their licenses revoked, the provincial education department said at the weekend.

Experts said the move might help raise the moral standards of teachers and prevent school rapes.

Li Yingqing and Guo Anfei contributed to this story.

huyongqi@chinadaily.com.cn