Mr Mitchell, who is standing down at the election, made his comments in an interview with The Independent on Sunday, in which he was asked about the prospects of Ukip taking the constituency where it is mounting a strong challenge.
“There is no chance we’ll lose Grimsby, even if we selected a raving alcoholic sex paedophile we wouldn’t lose Grimsby,” he told the newspaper.
His comments were condemned by Ukip candidate Victoria Ayling, who accused him of taking voters for granted.
“Austin Mitchell has been a respected constituency MP but he’s assuming that people don’t think very carefully about how they vote. People do think very carefully and I don’t like Mr Mitchell insulting the people of Grimsby,” she told the paper.
Mr Mitchell responded by accusing The Independent on Sunday of “bad journalism” saying his comment was a response to an attack on Grimsby and the Labour candidate, Melanie Onn.
“Making summation of nowt,” he wrote on his Twitter feed. “Was a response to an attack on Grimsby and Mel. Grimsby is loyal, Labour & Great.”
Bradford-born Mr Mitchell, who is now 80, has been the MP for Great Grimsby since he won a by-election in 1977.
A former journalist who worked on the ITV Calendar news programme, he famously chaired a live studio debate between Brian Clough and Don Revie after Clough had been sacked by Leeds United in 1974.