Mostly French nationals, the men and women were declared martyrs by the Vatican in January 2018, since they were murdered "in odium fidei", or out of hatred for the faith.

Here is a summary of the killings.

- Four White Fathers -

On December 27, 1994 attackers armed with automatic rifles gunned down four missionaries at their rectory at Tizi Ouzou, about 100 kilometres (60 miles) east of the capital Algiers.

From the Missionaries of Africa order -- also known as the White Fathers -- they were French nationals Jean Chevillard, 69, Alain Dieulangard, 75, and Christian Chessel, 36, and Belgian Charles Deckers, 70.

Two days later, the radical insurgent Armed Islamic Group of Algeria (GIA) claimed responsibility, in rapid revenge for the December 26 killing of four of its men who had hijacked an Air France plane and were shot dead by French forces.

The group, the most radical of the insurgent organisations then at war with Algeria's secular government, said at the time its "forces will continue the extermination of Christian crusaders."

The four GIA hijackers seized the plane on the tarmac at Algiers airport on December 24, killing three of its more than 200 passengers and crew. After the plane landed at Marseille airport two days later, it was stormed by elite forces who killed the abductors and freed the passengers.

- The monks of Tibhirine -

On the night of March 26 to 27, 1996, gunmen stormed the Notre Dame de l'Atlas monastery in Tibhirine, about 80 kilometres (50 miles) southwest of Algiers, and kidnapped seven French Trappist monks.

The GIA announced on May 23 it had slit their throats, blaming the French government's refusal to negotiate with them.

Algeria's army said they found the heads of the victims on May 30; the bodies were never seen again.

The Algerian government maintained the massacre was another crime by the Islamists. But this version came into doubt after allegations from various witnesses that the army itself may have been responsible, either through blunder or to discredit the Islamists.

The seven were: Christian de Cherge, 59; Luc Dochier, 82; Paul Favre-Miville, 56; Christophe Lebreton, 45; Michel Fleury, 51; Celestin Ringeard, 62; and Bruno Lemarchand, 66.

- Bishop of Oran -

Bishop Pierre Claverie, 58, was killed with his driver on August 1, 1996 when a remote-controlled bomb exploded at his residence in Oran in western Algeria.

Claverie, a dual French-Algerian national, was attacked after returning home from a meeting with the then French foreign minister.

He had publicly condemned atrocities attributed to Islamic fundamentalists and his killing was blamed on the GIA.

The murder was met with outrage in Algeria and France, coming only weeks after the kidnapping and murder of the monks of Tibhirine.

- Killed in Algiers -

Two French nationals were gunned down in a library in the Casbah suburb of Algiers in May 1994. Of the 19 clergy to be beatified on Saturday, they were the first to lose their lives.

Brother Henri Verges, 63, and Sister Paul-Helene Saint-Raymond, 67, were killed while they were helping young Algerians to prepare for their examinations. The GIA claimed the killings.

In October 1994 two Spanish Augustine nuns -- Esther Paniagua Alonso, 45, and Caridad Alvarez Martin, 61 -- were shot dead en-route to prayers in the residential, working class Bab El-Oued area.

In September 1995 two more nuns -- Jeanne Littlejohn, 61, of Maltese nationality and Denise Leclerc, 65, from France -- were shot dead returning from prayers in the capital's poor Belcourt district.

In November the same year French nun Odette Prevost, 63, was killed in an attack in the Kouba district, a working class area of central Algiers.

acm-br/jmy/dwo

AIR FRANCE-KLM