Chinese parents staged a protest on Sunday after six pupils were killed in a stampede at a primary school, as concerns over child safety mount.

AFP photos show riot police confronting dozens of parents, many of them wailing with grief as they clutched photographs of their children, near Mingtong Primary School in Kunming, capital of the southwestern province of Yunnan.

The group of parents held a banner saying "The killers should be severy punished" as they marched down the street, appearing to clash with a row of police who formed a line.

State news agency Xinhua said seven people had been suspended or removed from their posts following Friday's accident, which left 26 other children injured.

Officials said the children killed in the stampede were all in grades one and two, meaning they were likely six or seven-years-old.

Xinhua said the accident happened when a two-metre (6.6-foot) long cotton cushion used for gym class, which had been propped against a wall, toppled over and blocked a stairway corridor.

Several children were apparently trapped underneath and their schoolmates, streaming past, stepped on them without realising.

School safety is a major concern in China.

Four children died in a stampede at a school in the central province of Hubei last year when pupils left their dormitory on the fourth floor and attempted to exit the block. The ground floor gate was closed, resulting in the crush.