More than 100 more cases and 34 deaths from the new respiratory disease Mers-coronavirus have been reported by officials in Saudi Arabia.

The cases date back to February and came to light after an analysis of hospital records.

The World Health Organization says there have now been 820 cases of Mers and 286 deaths.

The exact source of the novel infection is still uncertain, but camels are a prime suspect.

The virus is from the same family as the common cold, but can lead to kidney failure and pneumonia.

It was first detected in June 2012.

The update from the Saudi authorities said there were 113 additional cases - 76 of the patients recovered, three are still in hospital and 34 have died.

Cases have also been confirmed in Jordan, Qatar, the United Arab Emirates, France, Germany, Italy, Tunisia, Egypt, the UK and the US - usually after travel to Saudi Arabia.

Source?

Researchers believe the coronavirus that causes the infection crossed over from animals.

Earlier this month, a report in the New England Journal of Medicine found “identical” Mers viruses in camels and their owner.

However, the link had not been conclusively proven and some researchers argue there may be another source.

The figures do show that nearly half of the cases were spread between people. It seems to have spread after close contact with family member or medical staff.

The World Health Organization does not recommend restrictions on trade or travel, but does warn people to avoid raw camel milk, camel urine and to ensure meat is properly cooked.