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The pair were set to play in South Africa's new twenty20 competition but the tournament has been postponed for a year.
The league was billed as South Africa's answer to India's IPL and Australia's Big Bash.
It was due to start on November 3 but Cricket South Africa (CSA) has been unable to secure a broadcast deal or a major naming sponsor and has put back the start date to November 2018.
It is major setback for McClenaghan. The left-armer pace bowler got released from his New Zealand Cricket contract to play in both the Australian Big Bash and the South African T20 Global League, while McCullum was a big-name signing alongside the likes of West Indies batsman Chris Gayle and former England international Kevin Pietersen.
South African Cricketers Association (SACA) has called for an independent review in the wake of the announcement.
``This has a very significant impact on a large number of local and overseas players, all of whom have signed contracts to play in the league,'' SACA chief executive Tony Irish said.
``Some players turned down other opportunities in order to commit themselves to these contracts. We will be looking at all implications of this for players, including what compensation should be paid to them.''
New Zealand Cricket Players Association chief executive Heath Mills believes CSA has a ``moral obligation'' to honour the contracts.
``Firstly, it is disappointing that this event has fallen through and it does not sound like it has been managed well,'' Mills said.
``From our perspective it is really important that the player payments are honoured.
``Whether they are going to take that approach, I don't know but we are certainly working with Tony Irish to make sure they understand the importance of doing the right thing in that regard.''
Mills said while it was not good news for McCullum and McClenaghan, they might well pop up in the Bangladesh Premier League and there were other playing opportunities in leagues around the world.
The postponement of the T20 Global League will leave a six-week gap in South Africa's calendar with no domestic or international cricket scheduled during the period.