Scientists have developed what they claim could be the most potent treatment for severe pain - as potent as morphine.

A sea snail's saliva contains chemicals that help the slow-moving creatures catch prey.

These chemicals are injected into passing prey with hypodermic-needle-like teeth that shoot from their mouths like harpoons.

Scientists already have transformed one of these chemicals into a pain-reliever for humans, but it has to be injected directly into the spinal cord, limiting its use.

The upside is that there's no risk of addiction, according to the experts.

Australian scientists, meanwhile, have developed an oral form of the painkiller that can work in low doses.