The World Health Organization says a new virus that has killed one person and has left another person in critical condition does not appear to spread easily from person to person.

The United Nations agency said Friday it is working with its international partners to better understand the public health risk.

WHO says the origin of the new virus is unknown. Some scientists suspect the infection may have developed from animals.

The virus is, however, is the same family as the deadly SARS, or Severe Acute Respiratory Syndrome, that killed hundreds of people, mostly in Asia.

Both patients who have been confirmed with the virus have suffered rapid kidney failure. One was a Saudi Arabian man who died several months ago, while the other is a Qatari who traveled to Saudi Arabia before he became ill. He is currently in a London hospital.

WHO has not recommended any travel restrictions in connection with the new virus, but it is working closely with Saudi authorities on health measures for Muslims making the upcoming hajj pilgrimage to Mecca.