The Egyptian military have launched a major offensive against Islamist militants in the northern Sinai Peninsula, with the operation described as the biggest of its kind in recent years.

At least 31 people were killed or injured after helicopters and tanks attacked villages on the Israel-Gaza Strip border. Another 15 people were detained during the operation, an undisclosed Egyptian security official told Reuters.



The counterinsurgency offensive is aimed at “cleaning” the areas of the Sinai where Islamic militants operate, including the border towns of Rafah and Sheikh Zuweyid, AP cited another military official as saying.



The major counterinsurgency offensive is aimed at “cleaning” those parts of the Sinai where Islamic militants operate, including the border towns of Rafah and Sheikh Zuweyid, he added.



A witness told the agency that a column of tanks, infantry trucks, rocket launchers and other military vehicles were seen in the area.



Meanwhile, the Egyptian military have diffused an explosive device on a railway line near the Suez Canal, the state news agency reported.



Multiple Al-Qaida-inspired militant groups have stepped up attacks on pipelines and security forces in the Sinai since the ouster of Egypt's president, Mohamed Morsi, by the army on July 3.



The situation remains tense in Egypt’s capital Cairo where a blast went off near a police station. There were no reports of casualties.



Protests against the military rule continue across the country, with three people reported killed in clashes as pro-Morsi demonstrators took to the streets of Cairo and the country’s second largest city, Alexandria, on Friday.



On Thursday, a suicide bomber attacked the motorcade of Egypt’s interior minister, Mohamed Ibrahim, with the official escaping unharmed in a massive explosion, which rocked the capital’s Nasr City district.