Chinese police have dragged away more than 100 parents while they were protesting the deaths of their children in poorly constructed schools that collapsed in last month's earthquake.

The parents, many holding pictures of their dead children, were pulled away from a courthouse in Dujiangyan, a resort city northwest of the Sichuan provincial capital, Chengdu.

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"Why?" some of them shouted.

"Tell us something," they said as police removed them.

The parents had been kneeling in front of the courthouse shouting, "We want to sue."

Their children attended a high school in Juyuan, near Dujiangyan, where 270 students died.

The Southern Metropolis News quoted a rescuer as saying that rubble from the school showed that no steel reinforcing bars had been used in construction, only iron wire.

The government says the May 12 earthquake destroyed a total of seven-thousand classrooms.

Many parents have accused contractors of cutting corners when building the classrooms, resulting in schools that could not withstand the 7.9-magnitude quake.

Pictures of collapsed schools surrounded by buildings still standing have fuelled anger.

Police dragged an Associated Press reporter and two photographers who were covering the protest up the steps into the courthouse, trying to prevent them from seeing the demonstration.

There were also several Japanese reporters at the courthouse.

Calls to local police were not answered on Tuesday.

One witness who did not want to be identified said police told the parents that the Japanese media was reporting "bad things" about them.

Chinese Foreign Ministry spokesman Qin Gang said on Tuesday that the government had been unusually open about allowing journalists to report on the earthquake and its aftermath and that China's "principle of transparency and openness remains unchanged."

He said local authorities were making decisions based on the conditions in the disaster zone, but they were not trying to block any news or make it difficult for reporters.

The protest happened while Li Changchun, China's fifth-ranked ruler, was touring other parts of the city.

The official Xinhua News Agency said Li was checking heritage sites damaged in the earthquake.

The confirmed death toll for China's worst disaster in three decades was raised to 69,107 on Tuesday, an increase of about 90 people from a day earlier, and 18,230 people are still missing, the State Council said.

The quake also left five million people homeless.