Amini's agent reacted furiously after Dortmund's reported offer of $135,000 was turned down by the club, followed, he claims, by a demand instead of $700,000.

Buddy Farah said over the weekend: "When I originally sat down with Lawrie McKinna and Graham Arnold we set a valuation of €200,000 ($270,000).

"Then Dortmund receive a letter from Mariners chairman Peter Turnbull saying the club wants €700,000 plus 20 per cent of future sales.

"They saw it as unrealistic and they are no longer interested in further discussions."

He added: "The way the European landscape is, what club would pay any more than $300,000 for an 18-year-old player, especially from Australia?"

Amini impressed the Bundesliga side in trials in March but since then the Mariners have lost influential playmaker Patricio Perez who has returned home to Argentina.

Mariners coach Graham Arnold is now expecting Amini to fill the hole left in the first XI by Perez's exit - and the club now ebelievs he's worth far more to them than Dortmund's last offer.

“There was an offer there and we rejected that, it was an insulting offer,” Turnbull told the Central Coast Express Advocate. “We then put a reasonable proposal to them and they rejected it.

"What people need to take into account is that Mustafa now takes extra special significance at the Mariners now that Perez  is no longer at the club.

“It will take a special offer for us to let him go. We’re not greedy, we are trying to do the best for the team and our supporters.

“We’ve never been a club to undertake contract negotiations through the media and that will never change. Some of the numbers quoted in the media have not been correct, we’ll leave it at that. Our offer was fair.”

Coach Arnold added: “Musty will play against Celtic (in a friendly on July 2) and I’m preparing for life with him next season.

"We no longer have Patricio at the club so Musty is a very important part of our plans."