Egypt has executed eight men sentenced to death over deadly attacks claimed by the Islamic State group on churches and a police checkpoint, judicial and medical sources said Tuesday.

The convicts, whose final appeal against the death penalty was denied in May last year, were put to death at dawn on Monday, the sources said. They were among 17 defendants who were sentenced to death by a military court in October 2018 for their roles in the attacks on churches in Alexandria, Cairo and Tanta and a police checkpoint in southwestern Egypt, a judicial source told AFP.

The other nine were tried in absentia and remain at large. The four attacks in 2016 and 2017, mostly targeting Christians, killed a total of 88 people. The Coptic Christian minority makes up between 10 and 15 percent of Egypt's 100 million population and has been particularly targeted by IS.

Executions have risen sharply since President Abdel Fattah al-Sisi took power in 2014 after leading the army's overthrow of Islamist president Mohamed Morsi.

Human rights group Amnesty International, which opposes the death penalty, said the severity of the convicts' alleged offences was no justification for their group execution. "A mass execution is no way to deliver justice. These men were executed following an unfair military trial," it said. "Everyone is entitled to a fair trial, regardless of the charges that they are facing."