CAIRO — President Mohammed Morsi's office on Monday condemned the killing of four Shiite Muslims by a Sunni mob, reportedly incited by ultraconservative Salafis, in a village near Cairo.
It said in a statement that authorities will not be "lenient" with anyone who interferes with the nation's security and stability or harm its society.
The statement echoed one issued earlier by Prime Minister Hesham Kandil.
Both said the culprits must be quickly found and brought to justice.
Egypt is an overwhelmingly Sunni Muslim nation with a tiny minority of Shiites. About 10 percent of its 90 million people are Christians.
According to security officials, the Sunday attack came after Salafi preachers in the village of Zawiyet Abu Muslim gave a small local Shiite community an ultimatum to leave the town by sundown. They said Salafis also joined the crowd. They spoke anonymously as they were not authorized to talk to reporters.
The incident also comes among a broad rise in hostile statements made against Shiites, including by the president's hard-line allies, fed in part by the growing sectarian overtones of Syria's civil war.
The killings came a week after Salafi clerics insulted Shiites during a June 15 rally attended by Morsi, who listened silently.
One cleric, Mohammed Hassan, called on Morsi "not to open the doors of Egypt" to Shiites, saying that "they never entered a place without corrupting it."
Egypt's Salafis have vehemently objected to the arrival in Egypt of tourists from Shiite Iran, forcing authorities to suspend their tours before allowing them to resume later. The tourists are not allowed in Cairo, home to some religious shrines revered by Shiites, flying directly to southern Egypt or Red Sea resorts.
Morsi's government has implicitly sanctioned travel to Syria by Egyptian volunteers who wish to join the mostly Sunni rebels fighting forces loyal to President Bashar Assad, a member of the Alawite sect, an offshoot of Shiism.
Assad's forces are backed by fighters from Lebanon's Shiite Hezbollah group, a longtime ally of the Syrian regime. Shiite Iran is Assad's chief foreign backer.
Egyptian volunteers have been fighting on the side of the Syrian rebels for over a year now, but the involvement of Egyptians in that nation's civil war is likely to widen after Morsi's decision to break diplomatic relations with Damascus and calls at the June 15 rally for jihad, or holy struggle, in Syria.