A newly-elected mayor in western Germany has been stabbed and left critically injured near her home, police say.

Iris Stalzer, 57, is a member of the centre-left Social Democratic party (SPD) and became the mayor of Herdecke in the North-Rhine Westphalia state in September.

Local police say a major operation is underway in the small town. Investigators are exploring all avenues but are not ruling out a family connection.

Chancellor Friedrich Merz condemned what he called a heinous act, adding: We fear for the life of the mayor-elect, Iris Stalzer, and hope for a full recovery.

The SPD expressed deep shock among its members regarding the attack.

Officials report that Stalzer's two adopted children - a 17-year-old daughter and a 15-year-old son - made an emergency call to authorities around midday local time. They were later taken for questioning and forensic investigation. Eyewitnesses at the scene noticed a teenager entering a police vehicle.

This summer, a domestic violence incident within the family was recorded by police, security sources disclosed.