The outbreak of the deadly MERS virus has receded, but the coming mass pilgrimage to Saudi Arabia called the Hajj poses a risk of spreading the disease, the World Health Organization said on Tuesday.

Reported to have infected more than 800 patients, mainly in Saudi Arabia, the Middle East Respiratory Syndrome (MERS) virus causes coughing, fever and sometimes fatal pneumonia, the WHO said in a statement issued after the 6th meeting of its MERS emergency committee.

"The upsurge in cases that began in April has now decreased and there is no evidence of sustained human-to-human transmission in communities," WHO said in a statement.

However, "the situation continues to be of concern, especially given the anticipated increase in travel to Saudi Arabia related to Umrah, Ramadan and the Hajj," the UN health agency said.

The disease has proven to be fatal for at least 315 people worldwide, prompting a few cases to spread to neighboring countries such as Europe, Asia and the United States, Reuters reported.

Important steps are being taken by health officials in Saudi Arabia to study and control the virus, which travelers are carrying around the world.

The virus is considered a deadlier but less transmissible cousin of the Severe Acute Respiratory Syndrome (SARS) virus that appeared in Asia in 2003, killing hundreds of people, mostly in China, Agence France-Presse reported.

According to a preliminary investigation by the WHO, the likely source of MERS in humans has been directed towards close contact with camels.

"There have been significant efforts made to strengthen infection prevention and control measures," the WHO statement said. As a result, "the committee unanimously concluded that the conditions for a Public Health Emergency of International Concern (PHEIC) have not yet been met".

In October, millions of pilgrims will travel to Makkah for the annual Hajj, the pilgrimage which all Muslims must perform at least once in their lifetime, if they are able.