On Monday, the WHO said in a statement that "thirteen cases of wild poliovirus type 1 (WPV1) have been confirmed” in the Middle Eastern country.

The WHO also warned against the rapid spread of the virus, saying, “The risk of further international spread of wild poliovirus type 1 across the region is considered to be high."

"A surveillance alert has been issued for the region to actively search for additional potential cases,” the WHO added.

The WHO says the virus has probably spread from Pakistan and can pose a threat to all children across the Middle East.

"Genetic sequencing indicates that the isolated viruses are most closely linked to (a) virus detected in environmental samples in Egypt in December 2012" related to wild poliovirus detected in Pakistan, the organization said.

Last month, polio virus, which is transmitted via contaminated food or water, was confirmed among young children in the province of Deir Ezzor in the east of the crisis-hit country.

According to the WHO, more than 650,000 children in Syria, including 116,000 in Deir Ezzor, have already been immunized.

Almost all children living in the Arab country were vaccinated against the disease before the militancy broke out in the country.

The war in Syria started in March 2011, when pro-reform protests turned into a massive insurgency following the intervention of Western and regional states.

Since the start of the war al-Qaeda affiliated groups have been emerging under different names in Syria, fighting at the side of the US-backed opposition which is leading one of the bloodiest conflicts in the recent history.

According to the United Nations, more than 100,000 people have been killed and millions displaced due to the turmoil that has gripped Syria for over two years.

SHI/SHI