Egyptian army bombards Sinai militants
The Egyptian army has attacked militants in the Sinai peninsula using tanks and helicopters, killing or injuring at least 30 people.
Tanks, armoured vehicles and troops were deployed in towns along the border with the Gaza Strip, eyewitnesses say.
The operation is said to be the biggest of its kind in recent years in Sinai.
Elsewhere, soldiers discovered mortars and other explosives on a railway line near the Suez Canal, the state news agency reports.
There have been frequent attacks on pipelines and security forces since the uprising that toppled former President Hosni Mubarak in 2011.
On Thursday a powerful explosion targeted Interior Minister Mohamed Ibrahim as he left his Cairo house for work. He survived unscathed, but officials say another person died.
Column of tanks
A military official, who spoke anonymously, told the Associated Press that the army would "clean" the areas in Sinai where Islamist militants operated.
This included the towns of Rafah and Sheikh Zuweyid, as well as nearby villages, he said.
A witness told the news agency he had seen a column of tanks, trucks carrying infantry, rocket launchers and other military vehicles. Smoke was also seen rising from the area.
The state news agency quoted security sources as saying that at least 30 people had been "killed and injured" but the number of casualties was expected to rise as the operation continued.
Up to 15 people were also arrested and weapons caches, vehicles and militant hideouts were destroyed, the sources said, in a report which could not be verified independently.
"This is by far the largest operation we have seen and the one we have been waiting for,'' Sheikh Hassan Khalaf, a tribal leader from the targeted area, told the Associated Press news agency.