Of all the school subjects, art has to be one of the least risky. Physics, maybe - but a bowl of fruit has never posed much of a threat to your average pupil.

But take art out of the classroom and health and safety can become a real issue. Just ask Xiao He and A Jun, two pupils from China. They were drawn to a river they were painting, but got trapped in silt four or five metres away from the river bank.

They were sucked down by the banks of the river in Chongqing and were soon buried up to their waists.

Luckily, classmates were able to raise the alarm and firefighters used wooden boards and tree branches to dig them out.

“They were struggling to escape when we got there so we shouted for them to stay still as they were getting sucked down deeper,” said a fire service spokesman.

A relieved A Jun said he was happy to use his imagination to paint from now on.