Punch has admitted that the tied model must evolve to offer greater protection for its tenants, in a letter to its licensees.
Punch tenanted boss Rogher Whiteside wrote to all tenants in the wake of the highly critical Business and Enterprise Committee report into pubco power.
He said the pubco had a "long period of change ahead" and re-iterated that it was spending £1.6m a month on tenant support and had ceased upward only rent reviews.
"However, we do acknowledge that the tied business model needs to evolve further to protect your interests and to make the relationship more open and transparent.
He added: "Punch remains committed to improving the workings of the tied model. We will be writing to MPs to confirm that we will actively co-operate and work with the Government, MPs and key stakeholders to address any issues raised, to ensure that the tied model continues to provide robust support for the great British pub."
Whiteside said he was "concerned" a Competition Commission inquiry would only "create more uncertainty" in the industry.
However, one Punch host replied: "The long period of change ahead of us is too little, too late and will now take too long.
He added: "The trouble is any change would have to be to your benefit, otherwise why would you do it? The situation therefore must be taken from your hands to have any positive effect on the British pub trade — and that is urgently needed."