LONDON — Global health officials are closely monitoring a new respiratory virus related to SARS that is believed to have killed at least one person in Saudi Arabia and left a Qatari citizen in critical condition in London.

The germ is a coronavirus, from a family of viruses that cause the common cold as well as SARS, the severe acute respiratory syndrome that killed some 800 people, mostly in Asia, in a 2003 epidemic.

In the latest case, British officials alerted the World Health Organization on Saturday of the new virus in a man who transferred from Qatar to be treated in London. He had recently traveled to Saudi Arabia and is now being treated in an intensive care unit after suffering kidney failure.