Tottenham chief Daniel Levy has accused Frank Arnesen of betraying the club.
Spurs are in talks with Chelsea over compensation for sporting director Arnesen, who wants to join the Blues.
"Our supporters have openly used the word betrayal and I have to say it's probably appropriate," chairman Levy told the Sunday Mirror.
"I honestly felt Frank was going to stick to our agreement and that the challenge here at Spurs was one he enjoyed and relished."
Tottenham are due for more talks with Chelsea this week over a package that could include the transfer of midfielder Scott Parker to White Hart Lane.
But Levy remains unhappy after he brought the sporting director to the Premiership to work alongside coach Martin Jol.
"We had discussions with Frank in an attempt to persuade him not to consider the approach and offer by Chelsea," added Levy.
"It was in the club's interest to try to protect what we are trying to achieve at the club.
"There were offers of revisions to Frank's salary and, believe me, we made him significant loyalty offers.
"But it was evident from our conversations that I was powerless to talk him round and his mind was already made up.
"What we are all having difficulty reconciling is the Frank we knew, who was utterly charming and professional, in direct contrast to the man who clearly now wants to walk away from the commitment he had to us."
Tottenham have so far not complained to the Premier League over what they claim is an illegal approach for Arnesen but could do if they fail to agree a deal with Chelsea.