Five Saudis who died after contracting a new SARS-like virus last week had not travelled abroad, a health ministry doctor said on Saturday.
"After questioning relatives, it turned out that none of these people had been abroad before being infected," Dr Ziad Mimish, who heads the ministry's disease prevention unit, told AFP.
The outbreak occurred in the oil-rich Red Sea region of Al-Ahsaa, which is near Bahrain and Qatar.
The ministry was working closely with the World Health Organisation over cases registered in Saudi Arabia but did not need help from foreign medical teams, Mimish said.
A system was put in place across the kingdom to detect suspected cases and to monitor the condition of medics in contact with the patients, he added.
The WHO reported on Friday that three new cases of the virus were detected in Saudi Arabia, bringing to 27 the global total of confirmed cases, including 16 deaths.
The virus was first detected in mid-2012 and is a cousin of Severe Acute Respiratory Syndrome (SARS), which triggered a scare 10 years ago when it erupted in east Asia, leaping to humans from animal hosts.
The mysterious virus has been deadliest in Saudi Arabia, and the other cases were reported in Jordan, Germany and Britain.