The ex-England international has been linked with both jobs given Roy Hodgson's deal is set to expire at the end of Euro 2016, and Louis van Gaal is finding himself under increasing pressure at Old Trafford.
The coaching role he currently occupies with the Three Lions, and the illustrious playing career he enjoyed at Old Trafford while captaining the side between 2005 and 2011, has seen him touted as an attractive long-term option for either dugout.
But the pundit-turned-Valencia-coach, who was a surprise appointment at the La Liga outfit early in December, has insisted he would not be in either job in the short-term future.
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"Me being the England manager in six months or me being the Manchester United manager in six months – I can assure you it's not going to happen," he told The Telegraph.
"And it shouldn't happen. Simple as that. I am removing any doubt that anybody should be thinking in that way.
"You see these things and it's nonsense. Honestly, nonsense. I am happy here doing what I am doing. I am happy working under Roy. I have not been back to Manchester United for years.
"I am happy where I am."
Neville, who is still chasing his first league win at the helm of Valencia, happened to take particular issue with the suggestion that he is only using los Che as a stepping stone to either the England or United posts.
"The idea that I have taken this job so I can pounce on one of those other two jobs – it's absolutely not true," Neville insisted.
"You can rest assured of that. It's not going to happen in terms of people offering it to me and it's not going to happen in terms of me taking it.
"I want to be absolutely clear on that."