Oman extended the closure of its borders until February 8 after new strains of coronavirus were detected.
The sultanate closed its borders for a week on January 18 and the latest decision marks a second extension.
On Monday, Minister of Health Dr Ahmed Al Saeedi said Oman detected six cases of mutant strains, but did not specify which ones they were.
He said that the number of patients admitted to hospital with Covid-19 had doubled to 102 in two weeks.
"Doubling of the number is very worrying and frightening. We see individuals shake hands and embrace as if the virus and the pandemic have ended," Dr Al Saeedi said in a statement.
But he ruled out a total lockdown in Oman and said it was not “necessary for now”.
Last weekend, Oman received 100,000 doses of Oxford-AstraZeneca vaccines manufactured under licence by the Serum Institute of India, but the Ministry of Health did not say when the next round of vaccinations will begin.
On January 28, Oman announced an indefinite ban on public and private gatherings as daily Covid-19 cases increased.
The sultanate's supreme committee responsible for tackling the pandemic said the ban included educational institutions, weddings, conferences, seminars and exhibitions.
Oman began its vaccination campaign using Pfizer-BioNTech inoculations on December 7.
Since then, about 30,000 people have been vaccinated.
In a statement to Oman Television on Sunday, the Health Ministry urged people to take the vaccinations and not respond to rumours about the inoculations on social media.
Dr Al Saeedi said the next batch of Pfizer-BioNTech vaccines would arrive in six weeks, owing to problems faced by manufacturers.
The minister confirmed that Oman has ordered 2.5 million doses from Pfizer-BioNTech and other vaccine makers while orders for a further two million doses were being made.
Oman registered 198 more coronavirus cases and three deaths on Sunday.
The total number of cases in Oman is now 134,524, including 1,532 deaths and 126,949 recoveries.