By Li Hongmei

Scientists said on Wednesday they had found evidence that Sars-like coronaviruses can jump straight from a type of Chinese bat to humans without the need for an intermediary animal "host".

The find has "enormous implications" for public health control, with potentially pandemic viruses present in bats in China that could cause another outbreak, said the authors of the study published in the journal Nature.

"Even worse, we don't know how lethal these viruses would be if such an outbreak erupted," co-author Peter Daszak of the EcoHealth Alliance, a New York-based research group, said in a statement.

Bats have long been thought to be the origin of the Severe Acute Respiratory Syndrome coronavirus (Sars-CoV) outbreak that killed hundreds of people in Asia 10 years ago, but other Sars-like viruses found in bats lacked the genetic ability to "bind" to human cells for infection.

Sars had also been found in civet cats in wildlife markets in China, and many scientists believed the felines were a necessary intermediary host for the bat virus to mutate into a form able to target humans.

"Our current paper shows that this isn't necessary - we have found Sars-like coronaviruses in Chinese horseshoe bats that are much more closely related to human Sars and that can use the human cell receptor," Daszak told reporters by email.

"That means they could emerge directly from bats to people anywhere there is contact with this species of Chinese bat, not just in the wildlife markets where civets are also found."

The results underlined the importance of continued surveillance of viruses in bats to pre-emptively identify ones that could cross species, said the research team from China, Australia, Singapore and the United States.

"It is not uncommon for bats to be a food source for many people in China and other parts of Asia, so the risk is substantial," said an EcoHealth Alliance statement.

Horseshoe bats are also used in Chinese medicine.

The Middle East Respiratory Syndrome Coronavirus (MERS-CoV) which first appeared in September last year and has claimed 62 lives worldwide, is also believed to originate in bats - in Saudi Arabia.

The results published in Nature were based on a genetic analysis of virus samples taken over the course of a year from members of a horseshoe bat colony in Kunming.

Coronaviruses are a large family of viruses that cause an array of human illnesses - everything from the common cold to Sars. They also cause a number of animal diseases.