A Kenyan cardinal has called for the government to crackdown on extremism and for families to report suspicious activities by their children in the wake of the massacre of Christian students at Garissa University College last week. The four gunmen murdered 148 people and were later killed by Kenyan security forces when they managed to regain control of the university.

Archbishop of Nairobi Cardinal John Njue, chair of the Kenyan Catholic bishops, visited mourners at Chiromo mortuary and prayed with them.

He condemned the "heinous terror attack" against innocent, promising young Kenyans and others, and said the tragedy had brought Kenyans together.

"We have been touched by the generous support of Kenyans to the victims of the terror attack and their families and extend our gratitude and prayers to all who have touched the lives of these people in one way or the other," he said.

He urged Catholic priests, Church institutions and other Christian churches to continue supporting the families and victims of the attacks.

"We hope the government will get to the bottom of this problem of terrorism and radicalisation with a view to proactively stemming such incidences from recurring," he said. "In the meantime, we urge the government to beef up security especially in all educational institutions in the country and also address the now obvious breakdown in the security intelligence system."

He said he was "saddened" that many Kenyan youths were clearly being radicalised to commit acts of terrorism against their fellow citizens.

"We all need to join efforts and embrace a spirit of nationalism and patriotism among all of us. It is unfortunate that some terrorists are living among us yet we are not reporting them to the relevant authorities. We need to respect the dignity of all human persons."

He said everyone in Kenya had a responsibility to report suspicious behaviour to the authorities. He also called on parents, guardians and teachers to be alert to any "unusual, negative, suspicious or violent tendencies" in their children.

"Time has come for Kenyans to be more patriotic. Let us all be our brothers' and sisters' keepers," he said.

The Ministry of Education, the Teachers Service Commission, Boards of Management and University Councils should carefully and continuously vet all employees to ensure that they are not used to radicalise students and recruit them to join subversive groups.

He also urged religious leaders not to teach and preach "hatred for people who do not subscribe to their religion and doctrines."

Everybody believes in a "supreme being", he added, and everybody had an inalienable right to life and fundamental freedoms, especially to religious beliefs. They should not be perceived as "non-believers" if they do not subscribe to one particular religion.

Al-Shabaab, the terror group that has claimed responsibility, has threatened more attacks and has warned: "Kenyan cities will run red with blood."