Pope Benedict XVI arrives in the popemobile to celebrate a mass on Sunday in the outskirts of Luanda, Angola. (Andrew Medichini/Associated Press)

Two people were killed after deadly stampede broke out at a stadium a few hours before Pope Benedict XVI addressed young people in the Angolan capital of Luanda on Saturday.

The Rev. Federico Lombardi said the Pope is "very upset" by reports that two people were killed in the crush. The stampede broke out as the gates to Luanda's Coqueiros stadium opened hours before Benedict arrived, Lombardi said.

Portuguese news agency LUSA cited an unidentified source at a local hospital as saying a man and a woman were killed, eight others were hospitalized with minor injuries and 10 were given medical assistance at the site.

An Associated Press reporter saw another stampede break out when the Pope arrived, and at least 20 people were taken away in ambulances.

Tens of thousands of Angola's Catholics lined the streets of the capital Saturday for a blessing from the Pope, 81, who urged the country's faithful to reach out and convert people who believe in witchcraft.

Eighty per cent of Angola's 16 million residents are Christian, about 65 per cent Catholic.

The pontiff, wearing white robes, looked tired and moved slowly in the tropical heat during the late afternoon stadium appearance before about 30,000 people.

He gave a message of hope to young people, including some wounded and maimed during Angola's long civil war, which started with Angola's 1975 independence from Portugal and ended in 2002.

Benedict began his day addressing Catholic clergymen and nuns, telling them to be missionaries to those Angolans "living in fear of spirits, of malign and threatening powers. In their bewilderment they end up even condemning street children and the elderly as alleged sorcerers."

In Africa, some churchgoing Catholics also follow traditional animist religions and consult medicine men and diviners, who are denounced by the church. People accused of sorcery or of being possessed by evil powers sometimes are killed by fearful mobs.