Saudi Arabia said it had discovered 14 more cases of the potentially deadly Middle East Respiratory Syndrome (MERS) in the kingdom, bringing the total number to 313.
A health ministry statement on Friday said the new cases had been reported in the capital Riyadh, the coastal city of Jeddah and in Mecca in the past 24 hours.
Authorities had also registered five more deaths due to the virus, it said.
The jump in cases is of particular concern because Saudi Arabia will host pilgrims from around the world in July during the Muslim month of Ramadan, as well as in early October when millions of worshippers perform the annual Haj.
In total, 92 people have died of MERS in Saudi Arabia, the ministry said on its website.
Saudi Arabia has witnessed a jump in the rate of infection in recent weeks, with many of the new cases recorded in Jeddah, the kingdom's second-largest city.
A large proportion of the people infected are healthcare workers.
MERS emerged in the Middle East in 2012 and is from the same family as the SARS virus, which killed around 800 people worldwide after first appearing in China in 2002.
MERS can cause coughing, fever and pneumonia.
Although the number of MERS infections worldwide is fairly small, the more than 40 percent death rate among confirmed cases and the spread of the virus beyond the Middle East is keeping scientists and public health officials on alert.
A spokesman for the World Health Organisation in Geneva said on Friday it was "concerned" about the rising MERS numbers in Saudi Arabia.
"This just highlights the need to learn more about the virus, about the transmission, and about the route of infection," he said.
Saudi Arabia's King Abdullah replaced the health minister last week after growing public concern about the spread of the disease.
Saudi authorities say they have invited five leading international vaccine makers to collaborate with them in developing a MERS vaccine, but virology experts argue that this makes little sense in public health terms.