Residents of a city in the US Midwest have been on the receiving end of a targeted mailshot campaign by the secretive white supremacist organisation, the Ku Klux Klan.

Locals in O'Fallon, in St Charles County, Missouri, told of their anger and distress at finding leaflets in their letterboxes informing them that they were under KKK protection.

The flyers stated: "Neighborhood Watch. You can sleep tonight knowing the Klan is awake."

Residents reacted with outrage although many opted to voice their complaints off the record out of fear of reprisals.

One man, who identified himself only as Brian, said: "When I think of the KKK, I think of 1960s racial tension. You know, it's 2013. It's not really something you expect to see."

A woman resident said: "It's teaching hate. It's condoning it, and it's very wrong. We should not hate each other."

The city of O'Fallon, outside St Louis, has a population of nearly 80,000 and ethnically mixed. It was ranked one of the "Best 100 Places to Live" in 2006, 2008 and 2010 by Money Magazine.

KKK spokesman Frank Ancona said the flyers formed part of a national publicity campaign by the klan.

Leafleting was not illegal, even when done by the KKK, and was protected by civil liberties safeguards enshrined in the US constitution, said lawyers.

A previous attempt to block the KKK from distributing flyers in the city of Desloge, in southeastern Missouri, was defeated in a landmark legal victory for the American Civil Liberties Union.

A federal judge found in favour of the ACLU in March, ruling the flyers were protected by the US First Amendment, which guarantees freedom of speech.

The KKK, a far-right extremist organisation, flourished in the US Deep South in the late 19<sup>th and early 20<sup>th centuries. It has since splintered into several unconnected groups which number around 8,000 members in total, and has been classified a "hate group" by the US Anti-Defamation League.