"Speak to the printers," Mr Leon was quoted as saying on Sunday, "I've got nothing to do with this."
Weekend papers suggested that the latest local election posters for the party - which has mainly white support - showed party leader Tony Leon looking several shades darker than usual.
Mr Leon and his party have moved quickly to shrug off speculation that this could be a subtle attempt to win over black and coloured voters.
"Speak to the printers," Mr Leon was quoted as saying on Sunday, "I've got nothing to do with this."
He admitted that he had had a holiday in the sun, as well as a haircut, before the picture was taken.
But he dismissed as "bizarre" the light-hearted speculation that the new look was intended to appeal to dark-skinned voters.
'White politician'
He recalled the occasion on which President Thabo Mbeki - Mr Leon's main adversary in parliamentary debates - had referred to him contemptuously as "the white politician".
Mr Leon's spokesperson Ryan Coetzee said he was "greatly amused" by the media speculation.
"These stories can only be seen as a fulsome tribute to Krisjan Lemmer, who first brought up such mischievous speculation in his column," Mr Coetzee said.
Krisjan Lemmer is the pen-name of the Mail & Guardian newspaper's diarist - a name borrowed from a fictional character who was a notorious liar.
"I'm sure old Lemmer is pleasantly surprised to have been taken so seriously, an experience he no doubt would want to repeat in the future," Mr Coetzee said.
"Nevertheless, I assure both Krisjan and any other interested party that the photo of Tony Leon is an accurate representation of the real him."
While it is unlikely Mr Leon's party really did think a new look would make a big difference to the polls, he will need help if he is to break into the ANC vote bank when the municipal elections take place on 5 December.
The ANC, which leads the governing alliance, still has the support of an overwhelming number of South Africans.
So far the campaign has been a pretty low-key affair, and at least the poster row has brightened up a fairly lacklustre political battle.