Updated

Egyptian helicopter gunships and tanks pounded suspected hideouts of Islamic militants in the northern Sinai Peninsula on Saturday, in what officials described as a major new offensive in the insurgent stronghold. Residents who witnessed winding columns of trucks and armored vehicles pour into the area said the operation was one of the largest there in years.

Meanwhile, the country's prosecutor general filed new charges against deposed President Mohammed Morsi, accusing him of insulting the judiciary -- a crime punishable by up to six months imprisonment in Egypt.

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 Palestinian Gaza Strip, has long been a haven for militants including Al Qaeda-inspired groups. Attacks have spiked in the area 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.

Egypt's official news agency MENA reported that a total of six military helicopters were used to strike weapons caches and militants' vehicles in seven villages, as part of what it described as a "campaign to wipe out terrorist hideouts."

The army had jammed some communications in the area, and security forces took control of two telephone exchanges in order to disrupt communications between suspected militants, it added.

The security official also said troops had arrested an unidentified number of suspected militants but others managed to escape to mountainous areas in central Sinai.

In the past, militants used a vast network of underground tunnels linking Egypt with Gaza as a way to escape security crackdowns. However, over the past two months, the military has destroyed more than 80 percent of them, stemming the flow of weapons, militants and goods into Gaza, a territory under an Israeli-imposed blockade.

Another tribal leader in the area offered a different account of the operations, however. He called the raids "arbitrary," citing one incident where army troops attacked the house of a pro-government tribal sheik in the village of al-Dhahir. He spoke on condition of anonymity because of fear of retribution.

A leader of an ultraconservative Salafi group in el-Arish, Hamdeen Abu-Faisal, accused the government of spreading "false and fabricated reports" about targets and causalities in order to rally support from the population.
  The government says it is waging a "war on terrorism" against both the Sinai militants and supporters of Morsi, whose Muslim Brotherhood has organized street demonstrations to protest his overthrow and government assaults on protest encampments. Some followers have also staged apparent retaliatory attacks against police stations, churches, and other targets.

Abu-Faisal said that rising injustice, heavy-handed security policies and arbitrary arrest were the root causes of instability in the area.

"There are many question marks over the government-led operations in Sinai," he said. "There is violence and counter violence. But targeting the innocent, demolishing civilians' houses or destroying mosques serves no purpose."

An Egyptian journalist specializing in the restive peninsula has been under arrest since Wednesday. Ahmed Abu-Draa faces a military investigation on allegations of publishing false information about the security operation, taking photos of military installations without a permit and spreading rumors about the armed forces. A Sinai resident, Abu-Draa had questioned the military's statements about the operations. At During military airstrikes on a village that is a militant stronghold, he wrote on Facebook that the strikes hit civilian areas. He also accused military officials of misinforming the public.

Back in Cairo, the prosecutor general said Morsi had "assaulting" the judiciary by accusing 22 judges of forging election results in 2005, according to MENA.

The agency said 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 his resignation.

The ousted Islamist 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 from power. He has also been charged of inciting violence and the killing of protesters opposed to his rule during clashes in front of the presidential palace last December. He was referred to trial but no date has been set.

At least 2,000 of Morsi's fellow Muslim Brotherhood members have also been arrested, most on allegations of inciting violence. On Saturday, a Cairo court opened the trial of a leading group member, Mohammed el-Beltagy, a Salafi preacher, Safwat Hegazy, and two others -- all charged with of kidnapping and torturing a police officer. Security concerns however led the court to postpone proceedings until Oct. 5.

In addition to the Islamist roundup, the detention of Egyptian labor lawyer Haitham Mohammadain and journalist Ahmed Abu-Draa have raised concerns among rights activists that the military-backed government's crackdown on Islamists is expanding to silence other critics of its policies.

On Saturday, hundreds staged a protest in front of the general prosecutor's office in downtown Cairo and in front of the Press Syndicate to call for the two's release.

Successive violent clampdowns on pro-Morsi protesters have 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.

Egypt remains under emergency law and a nighttime curfew, security measures imposed by the interim government on Aug. 14.