The 18-year-old's agent Buddy Farah told The Sunday Telegraph that Turnbull asked for too much money from potential suitors Dortmund after they made an initial $135,000 offer in April.

At the time Turnbull labelled Dortmund's initial offer as 'disappointing'.

Farah said he had agreed with Mariners coach Graham Arnold and football operations manager Lawrie McKinna on a valuation which Turnbull went on to ignore.

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

"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."

Amini, who made 23 appearances for the 2010/2011 A-League runners-up last season, had impressed Dortmund management during a trial at the club in March prompting the initial offer.

Farah 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, who is likely to compete at the 2011 FIFA Under-20 World Cup in Colombia, has one year remaining on his contract with the Mariners.