Rival fans constantly called into question Webb’s professionalism and Liverpool’s Ryan Babel was even fined £10,000 for linking to a picture of him mocked up in a United shirt on Twitter following their FA Cup defeat in 2011.
But Webb, who retired from officiating last week to take up the role of technical director for the Professional Game Match Officials Limited, strenuously denies he ever gave United any favour.
“There’s no element of truth in it,” Webb said.
“It’s not something that affected me or played on my mind at all. It wasn’t hurtful. Much of it is tongue-in-cheek, of course.
“What does play on my mind is when I’ve made a mistake, particularly an influential one that has affected the outcome of a game. I’d be dishonest if I said it didn’t bother me.”
He added: “One newspaper listed the five games I’d want to forget over the course of my career. Well, there’s more than five. But against the backdrop of more than 500 professional games – I can think of many top professional footballers who have made plenty of mistakes but are still top professional footballers.”
Webb was considered by FIFA and the Barclays Premier League as one of the top referees in the world during his career. He officiated in two World Cups and was handed the finals of the 2010 World Cup and Champions League.
But that did not stop English fans questioning his integrity throughout his career.
Webb added: “If our integrity is questioned by people in a serious way, that’s a different matter. The level of integrity we have as a group is really high.”