A 26-year-old man in Germany has been charged with murder after confessing to shooting dead his parents and four other family members as they gathered for a funeral, prosecutors said Monday.

The accused, who turned himself in right after the shooting last January, has also been charged with two counts of attempted murder, the prosecutor's office in Ellwangen said in a statement.

The tragedy happened on January 24 at a restaurant in the town of Rot am See, near Baden-Wuerttemberg's state capital Stuttgart.

The accused "had been planning for a long time" to kill his mother and half sister, "allegedly because of abuse", the prosecutors said.

The man is currently being assessed by psychiatric experts, with prosecutors not ruling out a mental illness.

The suspect had joined a shooting club and legally acquired a handgun before the family came together for a funeral in the town where the accused lived with his father, who was separated from the mother.

The suspect opened fire on his parents first in the restaurant where everyone was gathering. He also shot dead his half sister and half brother as well as an uncle and aunt.

The victims were between 36 and 69 years old.

He also injured two other relatives as he fired off a total of 30 bullets in and around the building.