King Abdullah replaced the health minister, Abdullah al-Rabeeah, yesterday amid growing public disquiet at the spread of the disease, which was discovered two years ago and kills around a third of sufferers.
Rabeeah said on Sunday he did not know why there had been a surge but said it might be part of a seasonal pattern.
However, the jump is of particular concern as Saudi Arabia is expected to have a large influx of pilgrims in July during the Muslim fasting month of Ramadan, followed in early October by the arrival of millions of people to perform the annual Haj in Mecca and Medina.
Jeddah, Saudi Arabia's second-largest city where many of the new cases have been discovered, is the main entry point for pilgrims visiting nearby Mecca, site of the holiest places in Islam but where there have been no confirmed cases so far.
Last year's Haj passed without any new infections being identified.
The 17 new cases, announced late yesterday on the Health Ministry website, bring the total number of Saudi infections to 261, of whom 81 have died. Combined with the other 49 cases announced in recent days, they represent a jump of 34% in the number of laboratory confirmed infections within a week.
Saudi authorities last week issued several statements aimed at reassuring the public that there was no immediate cause for concern.
But Labour Minister Adel Fakieh, who has been appointed as acting health minister, was pictured yesterday touring a hospital in Jeddah, a display that seemed aimed at countering accusations from some Saudis on social media that the authorities had not taken the situation seriously enough.
MERS has no vaccine or anti-viral treatment, but international and Saudi health authorities say the disease, which originated in camels, does not transmit easily between people and may simply die out.