Rafa Benitez has revealed for the first time that he cannot guarantee he will be in charge at Newcastle United at the end of the season.

The Newcastle manager’s contract at St James’ Park ends this summer and Benitez can walk away for nothing, with the penalty clause that would have seen him have to pay £6million now invalid.

He had refused any attempts at a renegotiation, including the possibility of a short-term one-year extension, until he'd seen how the club had strengthened in the current transfer window.

Newcastle have still to sign a single player, after an attempt to take the left-back Jordan Lukaku on loan broke down on Friday night, and when asked if he could guarantee he would not walk out before the end of the season, he replied: “No, I cannot guarantee anything.”

Benitez’s fraught relationship with the club owner Mike Ashley has once more been stretched to breaking point following another transfer window in which his attempts to bolster the Newcastle first team squad have been thwarted.

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Ashley went into Benitez’s office at St James’ Park after a rare home victory against Cardiff earlier this month, but the Spaniard has admitted it was a fruitless visit, and that nothing has changed.

He has clashed with the club over recruitment for three of the last four transfer windows and had gagged himself from talking about the matter.

However, with the window due to close on Thursday, he spoke of his own future and then refused the opportunity of advising supporters to renew their season tickets, with deadlines approaching.

“That is not my business,” he said. “My business is to prepare the team against Manchester City and be sure they can compete until the end of the season.”

Newcastle fans have already planned a series of demonstrations against Ashley at Tuesday’s televised Premier League game with Manchester City at St James’.

Supporters will be handed DW Sports leaflets to hold up in an attempt to antagonise the Sports Direct owner, and there is a plan for a sit-in demonstration when the game has finished.

Against that backdrop, Benitez spoke of his impromptu meeting with the owner. “It didn’t change anything,” he said. “You just have more ideas. It’s exactly the same position.

Newcastle fans protest against Mike Ashley earlier this season (Getty)

“I had a conversation with Mike, Justin (Barnes), (Keith) Bishop and Lee (Charnley) the other day. We were talking about everything and now we will see where we are.

“I didn’t expect it (the meeting) but always, he’s the owner, he can do what he wants. I’m a professional and I’m fine. I know what I’m trying to do. They know my ideas. That’s it.”

He was asked if his patience would break, and replied: “I want to do things well. Again I will say, if I decide to stay in the Championship to do my job and to finish my job in the way that I like to do things. I have some principles and I will try to do things properly.

“Believe me, I can see where you are with your questions and I can see what is going around the fans, but still I have a cold mind, we have to stick together. We have to work hard together and it is the only way, and the best way, if we want to stay in the Premier League.

Benitez could wave goodbye to the club (Action Images via Reuters)

“What I have to give back to the fans is this: I am a professional, I will work hard and I will try to do my best.”

Benitez was asked why Newcastle had reached the 28th of January, deep in a relegation fight, and had not strengthened.

“It’s not a question for me,” he replied. “The way things are going on here, I can say yes or not to the proposals that I receive. I can give some names but I don’t do any negotiations, anything. In the end I can say yes or not so you give me this or that I can choose one or the other one. That’s it. I can say yes if we need that.”