Former Newcastle captain Alan Shearer believes wantaway striker Alexander Isak has poured “flames on the fire” of his stand-off with the Magpies by accusing the club of breaking promises, and said his comments “don’t benefit anyone”.

Isak has been trying to force a move out of Newcastle all summer but was frustrated earlier this month when the club rejected an offer from Liverpool, reportedly worth £110million plus add-ons.

Having sat out their pre-season tour of Asia and trained alone since, missing Saturday’s goalless draw at Aston Villa in Newcastle’s Premier League opener, Isak escalated the situation further on Tuesday night with a post on Instagram in which he said “the relationship can’t continue”.

Speaking to Betfair, Shearer said the situation is now an “absolute mess” as he pointed the finger at Isak’s agent Vlado Lemic.

“If I was him, I’d get his agent in a room and sack him on the spot immediately, because he is meant to be giving him the advice to sign that six-year deal and there’s no get out clause,” Shearer said.

“I mean, it’s ridiculous. And to take anyone’s word in football… it’s nonsensical to say that someone said, ‘Oh, I’ll be able to get out at the end of the season’. Really? I mean, come on…

“I’ve always said there are two sides to every story, but my feelings are exactly the same: he’s gone about it in the wrong way…

“I just think even releasing this statement last night has thrown flames onto the fire, which he didn’t need to do.

“I get that we needed to hear his side of the story and we’ve heard that now, and I’m not saying I don’t believe him or I don’t believe Newcastle, I’m just saying it’s very, very messy for him and for the football club. It doesn’t benefit anyone.”

In his statement, posted on Instagram on Tuesday evening, Isak had said: “The reality is that promises were made and the club has known my position for a long time. To act now as if these issues are only emerging is misleading.

“When promises are broken and trust is lost, the relationship can’t continue.”

Newcastle responded by denying that Isak had been granted any assurances over a potential move.

“We are clear in response that Alex remains under contract and that no commitment has ever been made by a club official that Alex can leave Newcastle United this summer,” a club statement said.

This is the latest episode in what has already been the primary saga of this transfer window.

Liverpool had a bid rejected at the start of August but have retained an interest in a player who scored 27 goals in 42 games for Newcastle last season despite signing Hugo Ekitike – a forward who was also targeted by Newcastle.

Newcastle are said to value Isak at £150million, and would only consider a sale if they have signed a replacement. As well as missing out on Ekitike, Newcastle were frustrated in their pursuit of Benjamin Sesko who chose to join Manchester United.

Isak has three years remaining on his contract at St James’ Park.

Isak’s representatives have been approached for comment.

Meanwhile, neither Newcastle nor Brentford were commenting on reports on Wednesday evening that the Magpies had seen an improved offer, said to amount to £40million in total, for Yoane Wissa rejected by the Bees.

The Tynesiders have been pursuing the DR Congo international to plug the gap left by the departed Callum Wilson for several weeks.

However, the PA news agency understands that even if they were successful on that front, that would not necessarily be good news for Isak, with Liverpool yet to approach their valuation and no sign of a direct replacement arriving at St James’ Park.