A car bomb in Egypt's restive Sinai killed 11 soldiers and another blast struck police in Cairo Wednesday, amid a wave of unrest following Islamist President Mohammed Morsi's July ouster.

The troops were killed when an explosives-laden car blew up next to an army bus in North Sinai's provincial capital El-Arish, a security official said. The army confirmed the attack, saying nine conscripts and two non-commissioned officers died.

At least one person was killed when Egyptian riot police stormed Cairo's Tahrir Square late Tuesday to disperse stone-throwing protesters, a health ministry official said.

Police backed by armored vehicles fired tear gas and shots after clashes in the square to scatter protesters who had gathered to mark the anniversary of deadly 2011 demonstrations.

An al-Qaida-linked group claimed responsibility on Tuesday for the assassination of an Egyptian officer involved in a crackdown on Islamists following the military's overthrow of president Mohamed Morsi.

Ansar Beit al-Maqdis said its militants gunned down Lieutenant Colonel Mohamed Mabruk on Sunday, vowing to carry out more assassinations of officers it accused of imprisoning female protesters.

Dozens of supporters and opponents of the army gathered in Cairo's Tahrir Square Tuesday to mark the anniversary of anti-military protests, amid mounting anger over a memorial to those killed in Egypt's uprising.

The 2011 demonstrations in central Cairo were against the Supreme Council of the Armed Forces, the military junta that took power after the fall of Mubarak.

Egypt said Monday its ambassador to Tunisia will return after being recalled in September following the Tunisian president's call for the release of Egypt's deposed president Mohammed Morsi.

Ayman Musharafa was recalled "because of Tunisian officials' unacceptable interference in the internal affairs of Egypt," Egyptian foreign ministry spokesman Badr Abdelatty said in a statement.

The head of Russia's state industrial holding company said on Monday that Moscow was on the verge of reaching a landmark agreement to deliver air defense systems to Egypt's army.

Rostec chief Sergey Chemezov's comments came in the wake of a visit to Cairo last week by Russian Foreign Minister Sergei Lavrov and Defense Minister Sergei Shoigu devoted to military and diplomatic ties.

Fifteen women and seven girls who back Egypt's ousted president Mohammed Morsi will stand trial for participating in clashes in Alexandria, the general prosecutor's office said on Monday.

The girls, all under the age of 18, will be prosecuted in a juvenile court, a statement said.

Gunmen shot dead an Egyptian officer in charge of the Islamist Muslim Brotherhood file at the interior ministry's national security agency, the ministry said on Monday.

The officer was gunned down while in his car outside his home late on Sunday, it said.

At least 26 people were killed in Egypt when a train ploughed into a truck and a mini-bus at a railway crossing early Monday, the health ministry said.

Another 28 people were injured in the accident, which happened south of Cairo.

An Egyptian minister on Sunday ruled out negotiations with the Muslim Brotherhood until the Islamists recognize the government's transition plan and renounces violence.

Social solidarity minister Ahmed al-Borei told Agence France Presse the Brotherhood must also accept Islamist president Mohammed Morsi's overthrow was a "revolution".