Benitez then said of Newcastle's fans: "They have to be concerned".
And after Newcastle's 4-0 friendly defeat to Braga in midweek, Benitez delivered a blunt transfer update which left many supporters anxious over his long-term future at the club.
Newcastle boss Rafael Benitez added: "I am really pleased to have Yoshinori Muto with us".
Benitez is a practised politician but he sounds at the end of his tether, with his latest complaints running much deeper than merely being a case of a manager putting pressure on his board before the closure of a transfer window.
Many Toon supporter groups are looking at using the game as a platform to show their anger towards the club hierarchy - something that will no doubt unsettle the players on the pitch.
Benitez is adored by the Geordie Faithful, but has something of a strained relationship with the North East clubs controversial owner Mike Ashley, and only last week admitted that he was anxious that he has not signed more players this summer.
Newcastle are running out of time to get deals done with the season just a week away. Mike Ashley isn't going to change for you.
The tweet immediately went down very badly with Newcastle fans, with many taking the time to vent their fury at the 61-year-old.
Talks broke down between the two clubs earlier this week.
"You're a very fearless man if you go out and criticise the owners, which to be fair is what he is doing", said Allardyce.
"And doing that as a manager in today's world is extremely risky; I couldn't see anybody else doing that!"
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