CAIRO: Egyptian authorities hanged six men convicted of killing soldiers Sunday, police said, ignoring appeals to spare them amid allegations that two of them had been in custody at the time of their alleged crimes.

Prosecutors said they were members of the Sinai-based Ansar Beit al-Maqdis jihadist group, which late last year pledged allegiance to the Islamic State group in Iraq and Syria.

A military court upheld the death sentences last March, following a trial in which the six were convicted of carrying out the attacks in the months after the army's overthrow of Islamist president Mohamed Morsi in July 2013.

Human rights groups had appealed for a stay of execution, saying two of the defendants had been in custody at the time.

Amnesty International said the men underwent a “grossly unfair” trial and that the only witness during the trial was a secret police officer.

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The sentence was carried out by hanging in a Cairo jail, the officials said.

Some of the men had been arrested when police and soldiers raided their safehouse north of Cairo in March 2014.

Two army explosive experts and six militants were killed in an ensuing gunfight, adding to the list of charges against the six men.

Read more: Imran criticises Morsi death sentence: 'Egypt should learn from Pakistan'