A teacher in northwestern China has been sentenced to death for raping 18 primary school girls, the second such case in the same area, state media reported Wednesday.

Xinhua News Agency said Cheng Laifu, a teacher in Changhe township in Dingxi city in Gansu province, was convicted of raping the 18 grade three and four students on 70 separate occasions between September 2001 and March 2005. The victims were 9 and 10 years old.

The ruling from the Dingxi Intermediate People's Court said Cheng even raped several of the girls at the same time.

"Cheng's crimes have had an extremely negative impact on society," the court said in its decision.

Calls to the court rang unanswered on Wednesday.

Xinhua said that in July 2005 Li Guang, also a teacher in Changhe township, was sentenced to death for raping 23 grade four and five students the previous year.

Xinhua said local education officials would not say if the two cases happened at the same school.

It said the court had conducted a closed-door trial.