WENZHOU -- Authorities in an East China city are looking into a suspected pollution that led to nosebleed among 20 pupils in a primary school, which was temporarily suspended, government sources said on Sunday.

The students from the No 9 Primary School in Beibaixiang township, Leqing City of Zhejiang province, began nose bleeding on Wednesday, while some of them also showed symptoms of vomiting, headache and stomachache.

An investigation by the environmental protection authorities in Leqing on Thursday showed that more than 30 factories or workshops are no farther than 1 km from the school.

Among the enterprises, 28 have not been approved of their exhaust gas emission, according to the investigation.

Two of the enterprises have obtained approvals, but their gas emission was not up to the standard, it said.

The investigators also found that the school was newly put into use, and the desks, chairs and some walls inside the classrooms were newly painted.

The government of Leqing announced on Saturday that environmental protection authorities would continue checking upon air inside and outside the school.

Meanwhile, the government will order suspension of production at the surrounding enterprises for a thorough overhaul.

The school has about 1,200 students and more than 60 teachers and staff workers.

Educational authorities in Leqing decided to shift the students to an old school to resume classes on Monday.