Al-Jazeera TV has shown what claims to be a video showing al-Qaeda militants preparing and carrying out last month's deadly bombings in Algeria.
The attacks were the worst in Algiers for years
The footage showed people handling wires and detonators, and then a large explosion, filmed from a distance.
A double bombing in Algiers on 11 April killed 33 people and injured dozens.
A man said to be a leader of al-Qaeda's North African branch urges young people to join the fight, calling it "a chance in a lifetime".
"We bring good tidings to our nation and youth and tell them that the list of martyrdom-seekers has become long and is growing every day," said a bearded man named as Abu Musab Abdul-Wadud, a leader of the al-Qaeda Organisation in the Islamic Maghreb.
"This is a crusader war on Islam and a battle of destiny between the infidels and believers so do not miss out... come to a paradise that is as wide as earth and the skies," he said.
The April attacks were the deadliest in the Algerian capital since 2002.
A long civil war that killed about 200,000 people had seemed to have died down, but the group has announced its intention to escalate attacks.