The 20-year-old forward had been named by coach Jan Versleijen in his 21-man Young Socceroos squad for the World Cup in Colombia which runs from July 29 to August 20.

However Leckie has impressed Moenchengladbach during pre-season following his move from Adelaide United, prompting the German club to move to ensure he is part of their preparations for the new campaign.

au.fourfourtwo.com understands Moenchengladbach's initial efforts to have Leckie's participation at the U-20 World Cup waived were unsuccessful, although it had been agreed he would remain in Germany and link up with the Young Socceroos on July 25.

However the German Football League (DFL) got involved in the matter prompting the FFA to agree to let him remain with the Bundesliga club.

Moenchengladbach sporting director Max Eberl said on the club's website: "We have ultimately refused to release him.

"An U-20 World Cup is a nice experience for a player, but we need Mathew for the competitive season opener."

Leckie, who scored a double in Moenchengladbach's recent pre-season friendly against Aberdeen, had admitted last week that the Colombia trip wasn't the ideal timing.

"The World Cup is unfavourable. When I come back, I must start again from scratch," Leckie had said on the club's website.

Moenchengladbach's first game of the 2011-12 campaign is next Friday against Jahn Regensburg in the German DFB-Pokal, before their Bundesliga season begins on August 7 away to Bayern Munich.

Eberl said last week the fact that the U-20 World Cup overlaps with league seasons was unacceptable.

"It is simply unacceptable that such a FIFA tournament is scheduled so that there is overlap with league matches," Eberl said.

"The problem is not just with us, but many other clubs in Europe. But the interests of the clubs who pay the players seem to not count. "

Eberl explained the club felt there was more benefit for Leckie to be involved in a Bundesliga game against Bayern Munich than an youth international against the likes of Costa Rica.

au.fourfourtwo.com contacted the FFA today to confirm the decision, however at this stage there has been no official response.

Previously, Brent McGrath and Steve Lustica declined invitations to be part of the squad to focus on club duties.