Komodos are the world's heaviest lizard, typically weighing 70 kilograms and growing up to three metres in length. -AFP Photo

SYDNEY The world's largest lizard, the Komodo dragon, has a snake-like venom in its bite which sends victims into shock and stops their blood from clotting, Australian research showed Tuesday.

It had been widely believed that deadly bacteria in the carnivorous lizard's mouth helped kill its prey.

But magnetic resonance imagery has for the first time uncovered venom glands containing a shock-inducing poison which increases blood flow and decreases blood pressure, scientists say.

Lead researcher Bryan Fry said three-dimensional computer imaging comparing the Komodo's bite with that of Australia's saltwater crocodile showed it used a 'grip and rip' pulling manoeuvre to tear deep wounds, similar to a shark or sabre cat.

Fry surgically removed a venom gland from a terminally ill Komodo at Singapore Zoo for the study, and said it contained a highly toxic poison which would induce potent stomach cramps, hypothermia and a drop in blood pressure.

The venom also blocked the blood's clotting ability, he said.

'Such a fall in blood pressure would be debilitating in conjunction with blood loss and would render the envenomed prey unable to escape,' he said.

'These results are congruent with the observed unusual quietness and apparent rapid shock of prey items.'

Komodos are the world's heaviest lizard, typically weighing 70 kilograms and growing up to three metres in length.

They are native to several Indonesian islands and are considered a vulnerable species, with only a few thousand left in the world.

They live on a diet of large mammals, reptiles and birds but have been known to attack humans.

An Indonesian fisherman was in March mauled to death by a Komodo dragon after he ventured into a remote island sanctuary for the giant killer lizards.