Authorities are investigating the dissemination of antisemitic pamphlets in Pittsburgh neighborhoods, including the one in which a gunman killed 11 people in a synagogue in October.

Police said on Sunday morning the material was found in neighborhoods including Squirrel Hill, where a gunman entered the Tree of Life synagogue on 27 October and killed 11 people in the deadliest attack on Jews in US history.

A man who authorities said raged against Jews during and after the shooting has pleaded not guilty to numerous murder and hate crime charges.

Police said “such hate-filled material” would not be tolerated by residents, city officials or law enforcement.

A spokesman said police and the city department of public safety were “taking this matter very seriously and will follow every investigative avenue”.