CAIRO — Egyptian helicopter gunships and tanks pounded suspected hideouts of Islamic militants in the northern Sinai Peninsula on Saturday in a major new offensive in the insurgent stronghold, officials said.

The assault came after a long column of armored vehicles and trucks poured into the targeted areas in what residents said was one of the largest operations there in years.

Meanwhile, the country's prosecutor general filed new charges against deposed President Mohammed Morsi of having insulted the country's judiciary.

A security official said "dozens" of insurgent suspects were killed and wounded in the Sinai offensive, which comes two days after a failed suicide bombing targeting the country's top policeman in Cairo. Smoke could be seen rising from the towns of Rafah and Sheikh Zuweyid, and troops set up a cordon to prevent militants from escaping as others combed the area, he said.

The northern Sinai, which adjoins Israel and the Gaza Strip, has long been a haven for militants including al-Qaida-inspired groups. Attacks have spiked in the Sinai since Morsi's July 3 ouster, prompting the latest army offensive.

"This is by far the largest operation we have seen and the one we have been waiting for," said Sheikh Hassan Khalaf, a tribal leader from al-Joura, one of 12 targeted villages in the area. "Starting today, you will not hear of attacks on army or police checkpoints as before. They either have to flee or get arrested," he added.

He said helicopters had been hovering overhead since early morning, and had struck four cars of militants as they tried to flee. He said that at least 50 soldiers were going house-to-house through his village on foot, looking for militant suspects.

The government says it is waging a "war on terrorism" against both the Sinai militants and supporters of Morsi. His Muslim Brotherhood group has organized street demonstrations to protest his overthrow and subsequent deadly assaults on protest encampments, but some followers have also staged apparent retaliatory attacks against police stations, churches, and other targets.

In Cairo the prosecutor general charged Morsi with "assaulting" the judiciary for accusing 22 judges of forging election results in 2005, according to Egypt's official news agency MENA. Egyptian law treats insulting a judge as a crime.

The agency said that Morsi refused to answer questions in relation to the charges. Morsi has been held incommunicado since his July 3 overthrow by the military after millions took to the streets demanding that he step down.

The ousted Islamist president faces a long list of accusations, including conspiring with foreign groups to orchestrate a prison break during the 2011 uprising which forced longtime autocratic president Hosni Mubarak of power. He is also charged of inciting violence and killing of protesters during Dec. 5 clashes between proponents and opposition clashes in front of the presidential palace. He was referred to trial but no date has been set.

Successive violent clampdowns on pro-Morsi protesters sparked a wave of unrest across the country. In one of the most dramatic attacks to date, Mohammed Ibrahim, Egypt's Interior Minister in charge of security, survived a car bomb explosion in an eastern Cairo neighborhood. The Health Ministry said one was killed and 22 wounded, while the minister was unharmed.

For weeks, authorities have reported the discovery and defusing of bombs said to have been found in populated areas. On Saturday, three mortar rounds were found tied to railway tracks linking the Suez Canal cities of Suez and Ismailiya, according to a security official. He spoke on condition of anonymity because he was not authorized to speak to the press.

On Friday, MENA reported that two explosive devices were defused next to a Giza mosque.