CAIRO — Smoke billowed in the sky as Egyptian helicopter gunships rocketed suspected Islamist militant hideouts in the lawless northern Sinai Peninsula for a second day on Sunday, killing 11 suspected fighters as part of the largest military offensive in the region in years, military officials said.
The strikes paved the way for a ground offensive, allowing troops backed by armored vehicles to sweep homes of suspected insurgents. A military official said 11 militants and one soldier were killed in the fighting on Sunday. He said 10 militants had been arrested. A day earlier, two soldiers and nine militants were killed in the offensive.
Army officials said the assault aims to drive out Al Qaeda-inspired groups from several villages of the restive border region, where militants have established strongholds and built an unprecedented stockpile of weapons.
Also Sunday, a militant group in northern Sinai allegedly claimed responsibility for a failed assassination attempt last week on Mohammed Ibrahim, the country’s interior minister.
In a statement attributed to it on militant websites, Ansar Jerusalem, an Islamist extremist group, claimed that it was behind the attack on Ibrahim. The statement also said the head of the military, General Abdel-Fattah el-Sissi, who led a coup against former Islamist President Mohammed Morsi, is another target.
General Osama Askar of the Third Army told reporters that troops in the Sinai had seized at least 10 shoulder-fired Sam-7 antiaircraft missiles on Saturday. They were found in a mosque and in homes of suspected militants in the town of Sheikh Zuweyid, near the border with the Gaza Strip and Israel.
Western officials say thousands of shoulder-launched missiles went missing from Libyan arsenals since that country’s 2011 civil war. Egyptian authorities say Libyan missiles have been smuggled into the Sinai, and some of those have gone on through underground tunnels to Gaza.
Sunday’s airstrikes targeted the villages of el-Mahdiya and el-Moqataa on the outskirts of Rafah and Sheikh Zuweyid. One official said US-made Apache helicopters hit shacks, houses, olive farms, and cars used by militants.
Armed Forces spokesman Colonel Ahmed Mohammed Ali said that helicopters had provided air cover for what was ‘‘the biggest security operation’’ in the northern Sinai in years. Ali’s statement, posted on his official Facebook page, also said that 118 houses and farms used as hideouts had been demolished in the operation.
A second military official in Cairo said the military found heavy weapons, explosive belts for suicide bombers, mortars, rocket-propelled grenades, antiaircraft missiles, and maps with positions of the military in the region.
Residents witnessed columns of trucks and armored vehicles pouring into the area over the weekend.
Some said they hadn’t seen foot soldiers in their villages in decades. Communications were jammed for hours, as authorities seized control of two telephone exchanges.
All roads leading up to the northern region of the peninsula have been sealed off and troops have encircled a dozen villages. Some local tribal leaders have expressed relief over the operation, but others remain skeptical, saying innocent men have been arrested arbitrarily.
Over the past weeks, the military has also bulldozed homes along the Gaza border and caved in tunnels beneath them in preparations for creating a buffer zone to reduce weapon smuggling and militant crossings.
Officials say militants are believed to be responsible for a series of attacks in a region they overran after the fall of autocrat Hosni Mubarak in 2011. The region has seen a sharp increase in attacks since the overthrow of Morsi on July 3.
The Cairo-based military official accused Morsi of giving militants free reign to stockpile weaponry by making deals with them to cease attacks when he was in office in return for amnesty and a halt of military action against them.
The militants, officials say, belong to a number of extremist groups that seek the establishment of an Islamic caliphate in the northern Sinai based on a hard-line interpretation of the religion.
The groups reject the ideologies of Morsi’s Muslim Brotherhood group as too moderate and view their participation in elections as heresy. They have said their goal is to drive out the authority of the central government, not to restore Morsi to power.
The ability of militants in Sinai to strike security forces has been limited to the peninsula so far. Ansar Jerusalem was unable to carry out the planned attack in Cairo against the well-guarded interior minister, who was unharmed in the bombing.
But the group has carried past attacks on gas pipelines to Israel, and claimed to be behind a 2012 shootout along the Israeli-Egyptian border in which three militants and an Israeli soldier were killed.
In Cairo on Sunday, a virtually Islamist-free panel charged with amending the country’s now-suspended 2012 constitution convened for the first time as authorities push to roll back Morsi’s legacy and implement a transition plan for fresh elections.
Islamists have seen their clout drastically reduced — a radical reversal from the initial post-Mubarak period when they formed new political parties and won elections.