New York police refused to grant a permit for a klan branch - the Church of the American Knights - to hold a demonstration on Saturday.

Police say the white hoods violate a state statute that prohibits groups from congregating in public places while wearing masks or disguising their faces, except at authorised masquerade parties or other entertainment.

The BBC's Jane Hughes in New York: "Many New Yorkers are appalled"

A lawsuit was filed on Tuesday on behalf of the KKK by the New York Civil Liberties Union.

"Regardless of the message, the First Amendment says people have a right to express their views," said NYCLU executive director and veteran civil liberties campaigner Norman Siegel.

Mr Siegel said the statute violated the First Amendment and had rarely been used since it came into effect 150 years ago.

But a top city lawyer, Daniel Connolly, said the anti-mask law was constitutionally valid. "We intend to enforce it," he said.

Unusual support

The NYCLU has represented other groups in their battle with the city and Mayor Rudolph Giuliani over the First Amendment.

In 1998 and 1999, the NYCLU represented a group of black activists over the right to hold a Million Youth March for black youth in Harlem.

The city twice denied that group a permit and, twice, federal judges overturned the city's decision and ordered police to grant the group rally permits.

The KKK case has received backing from an ususual quarter as the Amsterdam News and black activist Al Sharpton's National Action Network filed friend of the court briefs backing the KKK's constitutional right to rally.

"The Amsterdam News believes the message of the Klan is repugnant," said Elinor Tatum, publisher and editor in chief of the black-oriented paper.

"The reason we filed a friend of the court brief was not in support of the Klan, but in support of the constitution."

White pride

The KKK contends its members wear hoods to protect their identities because they have been subject to retaliation.

KKK Grand Dragon James Sheeley said the group chose New York for the rally to promote white pride and to overturn the mask law.

The KKK expects between 50 and 80 demonstrators for a two-hour rally in front of City Hall in downtown Manhattan.