RIYADH (AFP) - A Saudi man has died of the coronavirus Mers, bringing the kingdom's death toll from the Sars-like virus to 42, health authorities said on Wednesday, adding a new case was registered.

The 38-year-old man who died in the eastern city of Hafr al-Baten had been "suffering from a severe lung infection," the health ministry said on its website.

It said that an expat in the western city of Medina suffering from chronic kidney failure was under intensive care after he contracted the virus, which began in the kingdom's Eastern Province.

Saudi Arabia is the country worst hit by Mers, which has killed 47 people globally.

The Saudi authorities say 84 people have been infected, representing the majority of those who contracted the virus worldwide.

Experts are struggling to understand Mers - Middle East Respiratory Syndrome - for which there is still no vaccine and which has an extremely high fatality rate of more than 51 per cent.

It is considered a cousin of the Sars virus that erupted in Asia in 2003 and infected 8,273 people, nine percent of whom died.

Like Sars, Mers is thought to have jumped from animals to humans, and it shares the former's flu-like symptoms - but differs by also causing kidney failure.