An Egyptian soldier was killed on Sunday during clashes with militants in the Sinai Peninsula, army spokesman Colonel Ahmed Mohammed Ali said.
The soldier died of his wounds after troops and security forces exchanged fire with militants in North Sinai close to the border with the Gaza Strip, Ali told state television.
Security officials told AFP that the soldier, Alaa Mohammed Eid, was shot in the stomach and succumbed to his injuries after being transferred to a Cairo hospital.
Militants earlier attacked a security building in the Sinai, sparking clashes, and three policemen were wounded in separate fighting in the area, security officials said.
The fighting erupted as armed men belonging to Islamic militant groups attacked the North Sinai security headquarters in the town of Al-Arish at dawn using rocket-propelled grenades and automatic rifles, one official said.
"They positioned themselves on the roofs of buildings opposite the security headquarters and launched the RPGs," the official said.
Fighting stopped after the militants fled the area.
"It seems they set off an explosive device at the security headquarters first before using the RPGs," the official said.
In a separate incident, fighting between militants and security forces in the town of Sheikh Zuwayyid near the border with the Gaza Strip left three policemen wounded, another official said.
Militants then attacked the Sheikh Zuwayyid police station. One woman and a child were injured in the ensuing clashes, the officials said.
Eight people were also arrested in a town south of Sheikh Zuwayyid.
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A security official said the eight have "connections to militant groups," but residents denied the allegations.
Egyptian security forces launched a campaign to crush increasingly brazen Islamist militants in the restive Sinai after an attack on an army outpost killed 16 soldiers on August 5.
The government had always struggled with militancy and smuggling in the region but lost its grip after an uprising overthrew president Hosni Mubarak early last year, prompting the collapse of his discredited police force and allowing the militants to flourish.
On Friday, Bedouin broke through the fence of the Multinational Force and Observers (MFO) peacekeepers' compound and set fire to an observation tower. In the ensuing clashes, two Colombians and an Egyptian were injured, a security official said.
Earlier this month, the army said its forces had killed 32 "criminal elements" in the ongoing Operation Sinai which was launched days after the border post attack.
"The operation will continue until its goals have been achieved... These are not just military goals but also developmental goals for the Sinai," Colonel Ali said at the time.
He said that during Operation Sinai 31 smuggling tunnels connecting Egypt to the neighbouring Gaza Strip had been destroyed.
But "there are 225 main tunnels and each has two to three openings," he said.
The tunnels trade, which analysts estimate is worth half a billion dollars a year, has played a significant part in Gaza's economy since Israel first imposed a blockade in 2006 following the capture of one of its soldiers, who has since been released.
They are used to bring in a wide variety of goods, including food, fuel and building materials in what many say is a lifeline for the Gaza population.
But they have also been used to smuggle weapons.
"We have seized arms, rockets, RPGs, automatic rifles," said Ali.