Egyptian President Mohamed Morsi visited the Sinai peninsula on Friday to meet with and reassure Coptic families who fled from the town of Rafah after receiving death threats, his Facebook page said.
This "will not happen again," Morsi told a group of local Bedouin tribal chiefs and other residents of the town of El-Arish, including Coptic Christian families, the official news agency MENA and participants said.
"Your security is our security," he said.
"What happened is an individual case which represents neither Egypt nor its children, Muslim or Christian. It's crime for which the perpetrators must be held responsible," MENA quoted Morsi as saying.
According to residents and officials in Rafah, on the border with Gaza, Christian families fled to El-Arish about 30 kilometres (19 miles) away after having received death threats from Islamists.
Leaflets were circulated in Rafah demanding that the Coptic community leave or be killed, residents said. A shop owned by a Coptic family was subsequently machine-gunned.
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Prime Minister Hisham Qandil denied the families had been "forced" to leave, but the National Council for Human Rights said the "threats" necessitated their departure.
Stringent security measures were taken for Morsi's visit, with hundreds of soldiers deployed at access points to the city, and armoured personnel carriers stationed on streets, according to a security source.
Al-Masri Al-Youm newspaper said the president was initially going to visit Rafah as well, but "for security reasons" decided to stay in El-Arish.
Egyptian security forces launched a campaign to crush increasingly brazen Islamist militants in the restive Sinai peninsula after an attack on an army outpost killed 16 soldiers on August 5.
The government has long struggled with militancy and smuggling in the Sinai but it lost its grip after an uprising overthrew president Hosni Mubarak early last year, prompting the collapse of his discredited police force.
Egypt's Christians, who make up six to 10 percent of the country's population of 82 million, have regularly complained of discrimination and marginalisation.
They have also been the target of numerous sectarian attacks.