Pope Francis has prayed for the victims of the Germanwings plane crash, as French authorities say they are making progress recovering the bodies of those killed in Tuesday's crash.

Francis offered the prayer after Palm Sunday Mass in St. Peter's Square at the start of Holy Week.

In France, Marseille prosecutor Brice Robin told German news agency dpa that he hopes to complete the recovery of bodies within a week.

Tests on the body of the co-pilot may provide clues on any medical treatment he was receiving.

Prosecutors say Andreas Lubitz deliberately slammed the plane into a remote mountainside in the French Alps. They say the 27-year-old co-pilot was hiding an illness and sick notes for the day of the crash from his employer.