Ramos quit the Spanish club on Friday and was appointed as Martin Jol's successor at Spurs on Saturday evening.
Sevilla might well be set for a hefty compensation fee from the White Hart Lane club, and Del Nido plans to report them to football's governing bodies.
He told the Sunday Express: "If Spurs wanted Ramos they had to speak to me, but they approached him directly.
"They have acted incorrectly and I shall report them to Fifa and Uefa to defend my rights."
Del Nido is not alone in his fury at the manner at which Spurs allegedly went about their business.
"I was watching the Uefa Cup ties on Thursday when Sky told me my assistant manager was off to Spurs," he said.
"What's that all about?"