AFL clubs could win the power to negotiate their own beer deals after the competition's most enduring sponsor has significantly cut its multi-million dollar arrangement with the league.

Carlton United Breweries has reduced its AFL contract midway through the beer company's latest 10-year deal in an occasionally testy negotiation which saw CUB accuse the league of last year promoting a rival beer company at the MCG.

CUB's marketing director Richard Oppy. Credit:Ashleigh Bonner

While both parties have denied the incident led to the brewer cutting its AFL deal reportedly by one third, Fairfax Media understands the negotiations were punctuated by some acrimony when CUB's new owners moved to cut their AFL sponsorship more than 12 months ago.

The AFL's commercial operations boss Darren Birch said it remained unclear whether clubs would now have the opportunity to negotiate their own beer rights. He said the league would work with clubs "to look how we can responsibly maximise the beer category".