Renegade BNP supporters were behind a leaflet entitled "Perverts in Politics" -- according to the BNPs Yorkshire regional organiser.

As Nick Cass distanced the official party from the leaflet, West Yorkshire Police were still investigating whether it constituted a criminal offence.

The document, which claimed to be printed by the so-called "Keighley Liberal Forum", was put through letterboxes in Keighley West ward, where there was a by-election yesterday

The local Liberal Democrats have accused those who printed the leaflet of being "cowardly and deceptive" and have reported the incident to the police.

A spokesman for Royal Mail traced the PO box number at the bottom of the leaflet to the Bankfield Road home address of BNP town councillor Angela Clarke. Her resignation from Bradford Council caused the by-election.

The BNP candidate for the Keighley West election, Ian Dawson, gave the same address to election nomination officials on official papers.

Both the Liberal Democrat and Labour parties, which contested the Keighley West ward, described the leaflet as "very distasteful".

However, BNP regional organiser Nick Cass said: "This leaflet has not been put out by Ian or his campaign team.

"I've spoken to Angela Clarke about it and she's upset about the fact that her PO box number was used."

He said "renegade" BNP supporters could have printed and distributed the leaflet without official sanction.

He said there was nothing to stop them "cutting and pasting" Cllr Clarke's PO box number onto the leaflet.

However, members of the Keighley branch of the Liberal Democrat party voiced their outrage at what they saw as a crude attempt to damage their party's reputation.

On Wednesday the Lib-Dems' Keighley website carried the headline: "BNP Publishes Fake Liberal Leaflet."

It continued: "Some people in Keighley have recently received a leaflet that carries the banner: 'Keighley Liberal Forum'.

"Its imprint says the leaflet is published by 'Liberals for Decency in Politics' and gives a PO Box number as the address.

"The PO Box in question belongs to the BNP in Braithwaite.

"Keighley Liberal Democrats strongly repudiate any suggestion that we have any connection whatsoever with the leaflet in question."

Judith Brooksbank, Lib-Dem agent, who reported the leaflet to the police, said: "It contains a nasty and distasteful picture that will be going through letterboxes and seen by children."

She said her party's legal team was investigating whether it was illegal to use a fake political party name on a supposedly official election document.

She said she received phone calls from residents who were disgusted with the content of the leaflet and had to assure them it was nothing to do with the Lib-Dems.

She said: "When we told them it wasn't us, they said, 'well we didn't really think it could have been you'.

"It was a blatant deception of the voters of Keighley West." She described the people responsible as "cowardly".

The Keighley News contacted Cllr Clarke but she declined to comment on the issue.