"All the 23 patients are travelers who returned home from a foreign trip except one, and two-thirds of them were travelers returning from a Hajj pilgrimage," Iranian Health Minister Kamran Baqeri Lankarani told reporters here in Tehran.
He stressed that the patients had returned from trips to the US, Thailand and Singapore and one of them was a relative of a Hajj pilgrim.
According to Lankarani, all the patients are cured or are under treatment.
He advised all Iranians to avoid unnecessary trips to countries with reported cases of the H1N1, not to kiss and shake hands with the people suspected of having swine flu and wash their hands persistently.
In the meantime, the World Health Organization said Friday swine flu has spread to nearly every corner of the globe, admitting that it was still unknown how the virus would mutate in the northern hemisphere's winter.
With the death toll still rising rapidly and countries rushing out new ways to check the spread of A(H1N1), the United Nations agency said it was only a matter of time before the pandemic which began in March affected every country.
The agency added that the A(H1N1) virus, which the WHO declared a pandemic in June, has resulted in around 800 deaths. Earlier this week, the agency had put the figure at over 700.
Swine flu is a contagious respiratory disease which is a mixture of bird, pig and human genes. The virus can spread to people who have contact with infected pigs. It spreads when an infected person coughs or sneezes around someone else. People can become infected by touching something with the flu virus on it and then touching their mouth, nose, or eyes.
People can't get swine flu from eating pork or pork products. Eating properly cooked pork is safe. Cooking meat to an internal temperature of 160°F kills viruses and bacteria.
The drug for curing the disease is named Oseltamivir, an antiviral drug that is used in the treatment and prophylaxis of both Influenza virus A and Influenza virus B which is now being produced in Iran.
Symptoms of swine flu are similar to the common flu: fever, cough, sore throat, body aches, headache, chills and fatigue, and sometimes diarrhea and vomiting. Swine flu also can cause pneumonia, which can make it hard to breathe.