Viking warriors were fuelled by a hallucinogenic herbal tea as they went on blood-thirsty raids across northern Europe, scientists claim.

The warrior culture of the Scandinavian Middle Ages was marked by Norse skirmishes with their neighbouring communities, that often involved looting and pillaging.

Elite fighters, known as berserkers who went into battle without traditional armour, entered into a state of animalistic frenzy before fighting, according to historians.

It is said that after the battles finished their anger subsided. Now scientists believe the secret behind their fearless rampages were mind-bending hallucinogens.

Known as 'stinking henbane', which is otherwise poisonous, the plant caused the warriors to strip naked for battle and launch into a frenzied attack.

A wood engraving by Hugo Vogel of a Norse raid under Olaf Tryggvesson, circa 994 AD

It would have made the infamous warriors unable to feel as much pain, as well as becoming 'unpredictable and highly aggressive' and causing them to 'lose touch with reality', according to researchers.

Karsten Fatur, an ethnobotanist at the University of Ljbuljana in Slovenia, said the Vikings could have made tea from the potent herb or drunk it with alcohol.

He told the Times: 'They could have made tea from it, they could have infused it into alcohol, they could have made an ointment of the plant in animal fat and rubbed it on their skin.

WHAT IS STINKING HERBANE? 'Stinking henbane' (Hyoscyamus niger) is a plant infused with tea or alcohol to make people feel less pain. It can cause feelings of delirium, inhibition loss and manic episodes when ingested. It also triggers visual disturbances, hallucinations, drowsiness and red skin. But is is also known to dull pain. Advertisement

'It would have reduced their sensation of pain and made them wild, unpredictable and highly aggressive.

'There may also have been dissociative effects, such as losing touch with reality. This might have allowed them to kill indiscriminately without moral qualms.'

Previous theories attributed to the Viking's terrifying fighting abilities were said to be large quantities of alcohol, insanity or psychedelic mushrooms.

Fatur agreed that the mushroom could have accounted for their delirium but believes it would have produced the 'come down' that followed.

He added: 'Though aggressiveness and hyperactivity may occur, these symptoms are rare and not seen as common markers of A. muscaria poisoning.'

Armies throughout history have used mind-alerting drugs to help their soldiers improve their fighting, including the Romans, US forces in Vietnam and Hitler's Wehrmacht.