Cairo: Egypt on Tuesday executed four Islamist militants following their conviction by a military tribunal of killing three military academy students in a 2015 bomb attack that also wounded six others.

The attack took place outside a stadium in the Nile Delta city of Kafr Al Shaikh as the military cadets were waiting for a bus to take them to the academy.

Tuesday’s executions at a prison in the Mediterranean port city of Alexandria bring to 19 the number of militants executed over the past week.

Authorities executed 15 militants on December 26 after a military court convicted and sentenced them to death over a 2013 attack on a military checkpoint in the Sinai Peninsula, home of a long-running insurgency by Islamist militants. An officer and eight soldiers were killed in that attack.

Six militants were hanged in a separate terror case in 2015 after being convicted also by a military tribunal. Rights groups say the legal process against all 21 was flawed. They also decried last month’s executions, arguing that at least one of the 15 was tortured in detention and that relatives were not allowed to see them on the day of their execution in accordance with regulations covering capital punishment.

The spate of executions follows an uptick in high-profile attacks by militants and repeated vows by President Abdul Fattah Al Sissi to use “brute force” to crush the insurgency, now spearheaded by a local affiliate of the extremist Daesh group. Al Sissi has also warned that he expected Daesh militants who had fought in Syria and Iraq to join the Sinai insurgency after the loss of their strongholds in the two countries.

On Friday, a militant killed at least nine people when he attacked a Christian church in a Cairo suburb and a nearby Christian-owned shop. On December 19, militants fired a guided rocket that damaged a helicopter at the airport of Al Arish during a previously unannounced visit by the defence and interior ministers to the Sinai coastal city. Daesh claimed responsibility for both attacks.

In the deadliest attack by militants on civilians, 311 worshippers were killed inside a mosque in northern Sinai on November 24. There was no claim of responsibility for the massacre, but witness accounts said the gunmen carried Daesh black banner.