Pope Francis Way of the Cross Easter
Pope Francis leads the Via Crucis (Way of the Cross) procession, commemorating the crucifixion of Jesus, at the Colosseum in Rome (Reuters)

Pope Francis denounced "the complicit silence" that was easing the persecution of Christians across the world, in the wake of the deadly attack by Islamic militants on a Kenyan university.

Christian students were reportedly singled out for execution by gunmen from the Somali-based al-Shabaab militant Islamist group who massacred almost 150 people during a seige at Garissa University College earlier this week.

The pontiff condemned the attack and decried the oppression of Christians elsewhere in the world during a Good Friday service.

"We see also today our persecuted brothers and sisters, decapitated and crucified for their faith in you, before our eyes and often with our complicit silence," the pontiff said according to Vatican Radio.

Christian refugees from countries facing Islamist insurgencies like Syria, Iraq and Nigeria, were among the cross bearers in the Way of the Cross ceremony in Rome.

Earlier Francis described the Garissa University killings as an act of "senseless brutality", saying he was left "deeply saddened" by the attack in a telegram of condolence to the Archbishop of Nairobi.

"His Holiness condemns this act of senseless brutality and prays for a change of heart among its perpetrators," the message read. "He calls upon all those in authority to redouble their efforts to work with all men and women in Kenya to bring an end to such violence and to hasten the dawn of a new era of brotherhood, justice and peace."

Meanwhile Kenya police have arrested five people in connection with the shooting, Interior Minister Joseph Nkaissery said.