M&C revealed in May that Punch had placed the package on the market, which is valued at £50m.
NewRiver Retail acquired 202 pubs from Marston’s for £90m in 2013, with the group announcing last month that good progress had been made in converting a number to convenience stores.
It is thought that the company is likely to keep some of the Punch package as pubs if the deal is successfully completed.
Last month, NewRiver said it had submitted a further six planning applications and successfully secured three consents in regards to the Marston’s portfolio, taking the total number of planning applications submitted to 45 and total planning consents received to 13.
It said the current portfolio EBITDA is performing 0.46% above the 4-year guaranteed income of £12.2m a year received from Marston’s.
Earlier this year, Punch said it its disposal programme was ahead of target at £57m and had been revised up to £80m for the full year.