Saudi Arabia has found 25 more cases of Middle East Respiratory Syndrome (MERS), the kingdom's health ministry has said.
Seven people were confirmed as having MERS, followed by 18 more on Saturday, the biggest daily increase in new infections so far.
The total number of cases in the kingdom is 396, of whom 109 have died.
The new cases include nine in Riyadh, 10 in Jeddah, four in Mecca and two in Medina. In July, many foreign pilgrims are expected to visit Mecca and Medina during Islam's fasting month of Ramadan. Millions more are expected in early October for the annual Haj.
On Friday, the US said it had discovered its first confirmed case of the disease in a man who had recently been in Saudi Arabia.
Egypt said it discovered its first case, also in a man who had been in Saudi Arabia, on Thursday.
Infections of MERS in Saudi Arabia, where it was discovered two years ago, have more than doubled since the start of April, but the total number of deaths has increased at a slower rate.
A higher number of people without symptoms are also being found with the disease, suggesting that the rapid increase in recent weeks is partly due to wider testing of people who have been in close contact with MERS patients.
MERS, a form of coronavirus like the more deadly SARS, can cause fever, coughing, shortness of breath and pneumonia.
However, it is not easy to transmit between people and the World Health Organisation has not advised any travel restrictions for Saudi Arabia.