BBC chief executive Barend van Graan said they had made the decision to withdraw the lock from the match based on a number of factors.
“This is a very important period of preparation for the 2014 Vodacom Super Rugby season and a vital stage of our squad’s pre-season planning, strength and conditioning,” Van Graan said in a statement.
“Even more important though is the management of our players after a very long season and as such, the heightened risk of key players getting injured can severely jeopardise our and their Super Rugby campaign.”
Van Graan said the BBC had for a number of years been clear that this period was an active rest and recovery period for their international players.
He said requests for matches like these need to be directed to the BBC through the SA Rugby Union (Saru).
On Saturday evening the Barbarians directly approached Van der Merwe to partake and on Sunday evening informed the BBC per sms of the player’s inclusion in the team, it said in the statement.
The BBC informed Steven Berrick, one of the organisers of the Barbarian match, that Van der Merwe had no permission to partake in the match against Fiji.
“It was a decision based on principle and BBC policy, made in the best interest of the Bulls team,” Van Graan said.
Van Graan confirmed that the BBC had earlier received a request through Saru to release JJ Engelbrecht to partake in this match, a request they also declined.