A U.S. Navy engineer pleaded guilty Monday to attempted espionage for Egypt after offering details on the layout of the nuclear-powered submarine USS Gerald Ford while under construction.

Mostafa Ahmed Awwad, 36, a civilian who worked at the Norfolk, Virginia shipyard where the highly sophisticated sub is being built, offered the information to an undercover FBI agent posing as Egyptian intelligence in September.

Egypt on Sunday referred 58 Islamists suspected of links with the outlawed Muslim Brotherhood to a military court over alleged "terrorist attacks" against the police and public property.

The authorities have waged a deadly crackdown against the Brotherhood since the army overthrew Islamist president Mohamed Morsi in 2013, and accuse the movement of being behind attacks against the security forces.

Twenty-five people were killed and 29 others injured on Sunday in two separate road accidents in Egypt, where poor road and traffic regulations kill thousands each year, officials said.

One accident took place on the highway linking Cairo to the Mediterranean coast further north when a minibus collided with a truck killing 13 people and injuring four, said a health ministry official.

An Egyptian court has sentenced 23 people to 14 years in prison for the killings by an angry mob of four Shiite men outside Cairo two years ago.

The four dead were among Shiites attacked in June 2013 by a mob of several hundred residents as they gathered at a house in the town of Abu Musallam.

An Egyptian court Saturday ordered the retrial of 16 people sentenced to death or long prison terms for their involvement in the deaths of 25 policemen in the restive Sinai peninsula.

They were among 35 people accused of involvement in a rocket-propelled grenade attack on a police bus in August 2013 that was travelling to Rafah, on the border with the Gaza Strip. 

Egyptian police were closely monitoring Friday the condition of the third assailant in a foiled suicide attack on Luxor's Karnak temple, who is critically wounded in hospital, officials said.

They were also hunting for three people suspected of aiding Wednesday's failed attack, a police official in Luxor said, after security services said they had narrowly averted a "massacre" of tourists at the popular ancient site.

Masked policemen raided Hassan Sultan's apartment at dawn last month and whisked his three sons to an unknown location, before charging them with membership of a "terrorist" group.

The siblings are among dozens of youth activists who have been arbitrarily arrested in the past two weeks as authorities press a crackdown on opposition, human rights groups say.

An Egyptian court on Thursday sentenced a policeman to 15 years in jail over the fatal shooting of a woman during a peaceful leftist rally, a court official said.

Shaima al-Sabbagh, a 34-year-old mother of a five-year-old, was struck by birdshot in January as police dispersed a small march on the fourth anniversary of the uprising that toppled president Hosni Mubarak.

Egyptian prosecutors contradicted Thursday police claims they had foiled a suicide and gun attack at the ancient Karnak temple by preventing assailants from entering the site.

Police said Wednesday the attempted attack was foiled after policemen asked to search bags in the trunk of a taxi trying to enter the site in Luxor and discovered a cache of weapons.

A foiled attack on one of Egypt's most popular ancient attractions was raising fears Thursday for tourism and foreign investment as the country tries to recover from years of political and economic chaos.

Bombings and militant attacks have been common since the army ousted president Mohamed Morsi in 2013, targeting security forces in retaliation for bloody repression of the Islamist's supporters.