The Western Mail (p5) reports that Mr Gregory made the claim after it was suggested that he had been among a number of senior party figures who had been rejected at the first stage of the selection process.
He said: 'Some people are deciding to play silly games. These claims are nonsense. I have not even applied some people are mischief-making.'
He added: 'Unison is supporting the process which the party is going through, which is based on equal opportunities and the interviewing selection criteria. We recognise some people will be disappointed by this, but we are clear the process has to be gone through.