A “secret deal” was struck to allow a zoo to continue using a public common as an overflow car park.
According to the Local Democracy Reporting Service, Bristol Zoo was granted a licence to allow it to use land on The Downs until 2039.
Campaigners said it diminished people’s enjoyment of the open space, and they were also “shocked” they had not been informed a new licence was granted.
The Downs Committee, which manages the site, has been approached for comment.
The licence allows the zoo to use land at Ladies Mile for customer parking for up to 28 days a year, including public and bank holidays, for the next 20 years.
A Freedom of Information request, submitted to Bristol City Council by the campaign group Downs for People revealed it had been renewed for 20 years on 1 January “in private” by the Downs Committee.
The committee is made up of Bristol councillors and members of the Society of Merchant Venturers, and its decision was not made public in any official minutes on the council’s website.
Susan Carter from Downs for People said: “This is a shocking decision, both in substance and in how it has been taken.”
The zoo has been using the land for overflow visitor car parking since the 1960s.
The arrangement was expected to come to an end last December after council permission expired, and zoo bosses promised in 2017 not to seek further planning consent.
Bristol Zoo has been approached for comment.
Ms Carter said: “Using The Downs for a 700-space car park on the best days of the year seriously interferes with people’s enjoyment.
“Until 2013 the Downs Committee debated the issue of licences for zoo parking publicly. No licence was for longer than five years.
“But now a decision to allow parking for another 20 years has been made entirely in private.”
A City Council spokesperson said the decision was taken by the Downs Committee, which “sits outside” of the council,