Egypt restricted the ability of Syrians to enter the country on Monday, with officials citing reports that a large number of Syrians were backing the Muslim Brotherhood, which is engaged in a bloody standoff over the military's ouster of Islamist leader Mohammed Morsi, according to The Associated Press.

The decision dealt a blow to Syria's main Western-backed opposition group that is leading the fight against President Bashar Assad from its headquarters in Cairo.

Egyptian authorities began requiring Syrians to get visas before arriving in the country, according to officials and opposition figures, many of whom live in the Egyptian capital.

Veteran Syrian opposition figure Haitham Maleh said he was held up for several hours at the airport in Cairo Monday before he was allowed entry — an exception made only "after several political sides intervened with Egyptian authorities" on his behalf.