BEIRUT (AP) -- 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.
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.
"This Egyptian decision is a reward to Bashar Assad for all the Syrians he has killed," Maleh said from the Egyptian capital Monday night. Dozens of Syrian families with no money were denied entry, he said, and two planes carrying Syrians were returned to Syria and Lebanon, where they originated.
"I have been living in Egypt for two years. I have an apartment and I have a bank account in Egypt," he said earlier from the Cairo airport.
Egyptian airport officials said the new measures followed reports that a large number of Syrians in Egypt were backing the Muslim Brotherhood and took part in violence after the ousting of Egyptian President Mohammed Morsi. The airport officials spoke on condition of anonymity because they were not authorized to speak to journalists.
In response, the Syrian National Coalition said it regretted any crimes committed by Syrian nationals in Egypt and said Syrians "must not be punished for individual criminal acts."
In Syria's conflict, which pits a rebel movement rife with Islamist groups against Assad's regime, the Syrian branch of the Muslim Brotherhood has played a large role in the attempts to create a leadership in exile. The organization is a weaker version of Egypt's Muslim Brotherhood but is still considered the most politically organized Syrian opposition group.
The opposition has found itself on the defensive after a series of setbacks at the hands of Assad's forces, which have been reinforced by Lebanese fighters from the Shiite militant group Hezbollah.
Meanwhile, the ruling Baath Party -- which has been ruling Syria since 1963 and is seen largely as a front for the Assad family's iron grip rule -- replaced its aging leadership, including long-serving Vice President Farouk al-Sharaa, a close associate and longtime Assad loyalist.
Al-Sharaa, 73, is considered as a somewhat consensual figure and his name was floated by the Turks last year as a possible figure to lead a transitional administration to end the country's civil war. Like the majority of Syrians, al-Sharaa is a Sunni. His removal from the Baath Party command may be a move by Assad to shore up al-Sharaa's future chances as a potentially acceptable figure to both sides during a political transition.
Syria's state-run television said the new Baath Party command, which is the party's top decision-making body, was chosen during a meeting of the party's central committee.
It published the names of 16 members of the new leadership, which included none of the party's old leaders except Assad.
A senior Baath Party official, Fayez Sayegh, told The Associated press that the reshuffle -- the first since 2005 -- was mean to "pump in new blood" in the party.
The opposition and Washington dismissed the change.
"This is an attempt to improve the image of the regime," senior SNC member Abdelbaset Sieda said. "But the decision-making group is the same and did not change."
U.S. State Department spokeswoman Jen Psaki said the U.S. does not recognize Assad's legitimacy. "We continue to ask him to step aside. But we know that we need to find a way to work with all parties to get back to the table," she said.
Also Monday, the opposition figure appointed in March and tasked with forming an interim government to administer rebel-held areas resigned, citing his inability to form a government. "I have decided to step down for the general good of the Syrian revolution," Ghassan Hitto said in a statement.
Other opposition members disliked Hitto's perceived proximity to the Qatari-backed Muslim Brotherhood. He had been effectively sidelined since his appointment -- a result of the rivalry between Qatar and Saudi Arabia, which are vying for influence among the Sunni-dominated Syrian opposition. Both countries have been prominent backers of forces struggling to oust Assad, but Qatar has recently taken a back seat.