Egyptian security forces stood guard at checkpoints as more than 100 cars, some carrying dozens of jihadists, took part in a funeral procession for four slain fighters in the northern part of the Sinai Peninsula on Saturday. A little known militant group, Ansar Jerusalem, said its men were the target of a reported Israeli drone strike in Egyptian territory that killed the four militants.

The strike was a rare operation that could indicate increased cooperation between Egypt and Israel against militants in northern Sinai after the ouster of Islamist President Mohammed Morsi from power last month. Egyptian security officials confirmed the men were killed in an airstrike.

Hundreds of people, including armed jihadists, tribesmen carrying weapons and family members of the dead took part in the funeral, where the bodies were displayed in the back of pick-up trucks draped by black flags inscribed with Islamic verses. The flags are often used by Al-Qaida militants, but also by Islamists. Some in the procession chanted slogans against Israel and Egypt's army, currently battling insurgents in the area.

The procession passed through checkpoints peacefully, though it is believed that many who were present are wanted by police for carrying out near daily attacks on security forces in Sinai. Security officials said the nature of the attack, possibly from an Israeli drone, made it difficult to try and stop the procession for fear of enflaming an already volatile situation.

The officials also said that since only some 50 fighters are known to them in in Sinai - while others remain unidentified - it was not immediately possible to distinguish between militants and others during the procession. They also said that checkpoints leading to the cemetery where the men were buried were manned by just a handful of personnel ill-equipped to take on such a large group of possibly well-armed fighters.

Ansar Jerusalem said in a statement posted on a militant website that a drone crossed into Egyptian airspace Friday and killed four fighters as they were preparing a cross-border rocket strike into Israel. It said the dead were members of Egyptian Sinai tribes and that the rocket squad's leader escaped.

It denounced the Egyptian military for allegedly having allowed the attack. "What is greater treason than the Egyptian army allowing the Zionist drones to violate Egyptian airspace now and then?" it said.

The statement's authenticity could not be confirmed, but it was posted on an Internet website commonly used by militant groups.

The strike is likely to increase tensions in the border region. Insurgents, who have close ties to Palestinian militants in the neighboring Gaza Strip, have stepped up attacks on police and military targets since the July 3 coup that toppled Morsi. Some residents of Sinai have alleged that Morsi did not clamp down hard enough on militants during his year in office out of concerns it would anger some of his supporters.

Egyptian security officials, speaking anonymously on Friday, said that a drone firing from the Israeli side of the border had killed five suspected militants. The conflicting accounts could not be reconciled. Both said the site of the strike was about five kilometers (three miles) inside Egypt.

Israel has maintained official silence about the strike.

A statement posted on the official Facebook page of Col. Ahmed Mohammed Ali, an Egyptian military spokesman, denied any coordination between Egypt and Israel for the latter to carry out a drone strike in Egyptian territory.

Egypt's border is "a red line" and its transgression is not permitted, he wrote.

However, the militant statement said that there was Egyptian air activity in the area but after the Egyptian aircraft withdrew, the Israeli drone attacked. A tribal leader in the area said that an Egyptian helicopter flew over the site a few minutes after the drone strike.

Additionally, Egyptian security officials speaking anonymously said the Israeli attack was launched in cooperation with Egyptian authorities.

Egypt's military and security forces have long been engaged in a battle against militants in the northern half of the peninsula. Militants and tribesmen have been engaged in smuggling and other criminal activity in the area for years.

Militants have fired rockets into Israel and staged other cross-border attacks on previous occasions.

In comments to the Associated Press that backed up the Ansar Jerusalem statement, a local member of the Sawarka tribe said two of the dead were from the tribe's el-Menaie family and lived in a village called al-Mahdiya. The security officials had said four of the dead were from the family.

Ansar Jerusalem has previously claimed responsibility for a 2012 shootout along the Israeli-Egyptian border in which three militants and an Israeli soldier were killed.

Late last year, the group released a video about a militant who was killed in August in a strike that Egyptian officials said may have been carried out by Israel. In the video, a Bedouin confesses to working as a spy for Israel for $3,000 a month and to placing an electronic chip on the man's motorcycle. He also said that Israeli intelligence officers crossed into Sinai several times and planted a bomb on the road leading to the man's home. Pictures were then shown of the Bedouin's severed head.