A Cairo criminal court has sentenced 26 people to death and one person to 15 years in prison for terrorism offences.

The defendants were tried in absentia on charges including planning attacks on ships passing through the Suez Canal, manufacturing missiles and explosives to carry out attacks, monitoring and planning to attack security targets, and possession of guns, automatic rifles, explosives and ammunition.

Investigations showed the defendants were calling for attacks on army and police personnel, Christians and tourists, all of whom they deemed infidels.

They also called for attacks on churches, the public and private property of Coptic Christians, public facilities, foreign and petroleum installations, and the Suez Canal.

Defence lawyer Mohammed Abdel-Aziz said the case goes back to 2010, when 27 people were charged with planning attacks on the Suez Canal, but were released due to lack of evidence. They were referred to court in November 2013.

Abdel-Aziz said the defendants' legal papers were sent to the Grand Mufti of Al-Azhar, a requirement before an execution in Egypt, in late February.

Five of the defendants are already in detention, but they did not attend the session, he added.

A retrial is expected because even those in jail were sentenced in absentia, Abdel-Aziz explained.

Egypt has seen a spike in terrorist attacks on security installations and personnel since the ouster of Islamist president Mohamed Morsi in July 2013.

Attacks have mainly targeted security personnel and installations. But a bomb on a tourist bus in Taba in February, which killed three South Koreans and one Egyptian, raised fears that civilian and economic targets could become the focus of attacks.

The government has blamed Morsi's Muslim Brotherhood and their Islamist allies for orchestrating the violence and plotting against the country.

Attacks in the Sinai Peninsula, Cairo and the Nile Delta have provoked comparisons with the Islamist insurgency of the 1980s and 90s.

The Muslim Brotherhood was designated a terrorist group in December 2013 and all its activities were banned. The group is also accused of cooperating with Palestinian group Hamas to attack the Egyptian state.

Morsi is facing four trials, including one for espionage involving Hamas.