The official Xinhua news agency said education officials confirmed that about 150 children survived of the 352 inside the school when it filled with floodwater from a nearby river.
But officials in Shalanhe township, Heilongjiang province, said the official death toll of 92, including 89 children, had not changed.
A local police official said 17 children were still missing but claimed the remaining 240 were "safe''.
Controversy continued to grow on Monday, as state media said the head of Shalanhe's public security office and the township governor were both detained for questioning.
The official China Daily said 30 more bodies were taken to a mortuary outside the area.
"According to officials from a mortuary in Ning'an (the city that Shalanhe belongs to), 92 bodies had arrived by Sunday,'' the newspaper said. "Thirty more bodies were reported to have been sent to another funeral home 100 kilometres from Shalan Township.''
An official at the Ning'an education bureau said it was difficult to determine how many people were missing because many families had left the area. Police officers were trying to find all local families to check how many people remained missing, the official said.
The flood hit the Chang'an primary school in Heilongjiang's Shalan town early Friday afternoon as 352 children, aged six to 14, and 31 teachers were present.
Police said many children drowned as water up to two metres deep filled classrooms.
The school was severely flooded because it was one of the lowest points in Shalan township, a local public security officer said by telephone.
Local hospitals were giving emergency treatment to another 17 schoolchildren and eight other people, including a teacher and a local official.
Recent heavy rain had caused flash floods to pour down from nearby mountains. Officials said the rain was the heaviest in at least 100 years.
The education bureau official said deforestation of the mountains meant that they had lost their capacity to retain rainwater. dpa bs pw
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