The Anfield chief believes Spurs boss Harry Redknapp's claims that he would like Keane at his club could constitute an illegal approach.

Liverpool have not officially reported the north London outfit to the Premier League, but Benitez has not ruled out doing so.

He said: "We have not decided yet whether we will take this further, it depends on their response."

Liverpool are particularly unhappy because of Spurs' complaints about the Reds' conduct when Keane moved to Anfield for £20million last summer.

That situation was only smoothed over when Liverpool apologised and made a donation to a charity of Tottenham's choice.

The capital club did make contact with Liverpool on Thursday, but Benitez said: "We have said to Spurs that we are not happy with them because of the comments from their manager about Robbie Keane.

"I do not think that they have come in with an offer. He has been training this week very well, he is our player and he is trying to make sure he is ready for the next match.

"I think he is a long-term part of our plans, I hope he scores a lot of goals."

Benitez added: "We are not happy with Spurs. We have told them we were not happy with their manager's comments in his press conference about Robbie.

"We were very, very correct when we signed Robbie even though Spurs were complaining. Now we have this situation to deal with.

"But Robbie has been fine. Spurs wanted the player but they had to do things properly.

"They have to make an official offer and we will say yes or no. You must do things properly, especially when you have complained about everybody when he first joined us."

Keane was dropped by Liverpool for last weekend's FA Cup tie against Everton, but returned to the squad at Wigan on Wednesday where he was a late substitute for Steven Gerrard.

The Republic of Ireland captain will be in the squad for Sunday's home match against title rivals Chelsea.