Berlin: An independent candidate running for mayor of the German city of Cologne was stabbed in the neck and severely wounded on Saturday while she was campaigning in the city, police said.

Henriette Reker and an aide were both severely injured by the attacker, a 44-year-old man, police said. Three other people who came to their assistance were also injured, though not severely.

Attacked: Cologne mayor candidate Henriette Reker. Credit:AP

Police said the attacker stabbed Reker and her aide about 9am (6pm AEDT) at an information stand for the Christian Democrats (CDU), Chancellor Angela Merkel's party. The other three people were injured immediately afterwards.

Eyewitnesses said the attacker went straight for Reker.