A group has criticised moves which could see homes built at a former plant nursery in West Ham Park.
The Friends of West Ham Park described a proposal for the site in Upton Lane, Forest Gate, as "appalling", but chairman of the City of London Corporation's West Ham Park committee said it will be of "great benefit to park users" by providing a source of funding for management and upkeep.
Roger Jones, who chairs the friends group, said: "Everyone I have spoken to is outraged by this proposal.
"The park has been a lifeline for so many people both before and during the Covid-19 pandemic. [It] has always been popular and well used.
"We desperately need more, not less, space. We will be fighting against this insult to the communities around the park in every way we can."
The West Ham Park charity, of which the City of London Corporation is a trustee, is exploring an option to redevelop what it says is a brownfield site, having been previously developed.
But the Friends challenge the designation, saying the whole area should be parkland.
The City of London says a requirement means half the site would be for operational buildings, parkland and recreational facilities, such as a community café and changing rooms.
It says homes would provide a source of funding for the management and upkeep of the park, with these being "the most viable form of development", generating money for West Ham Park charity and meeting a need for housing.
However, the Friends described the park as a "green oasis" in a densely populated neighbourhood. At 77 acres, the park is Newham's largest.
The City of London invests £40million a year in its 11,000 acres of green space in London and the south east. It reports most spaces are run as charitable trusts which use generated income to reinvest in the sites.
Plans to begin marketing the former nursery site over the summer and invite developers to submit bids have been approved by the City of London's West Ham Park committee.
Oliver Sells QC, its chairperson, said: "We are pleased to be moving forward with this project which will be of great benefit to park users.
"This is an opportunity to make effective use of previously developed land and we are excited to move on to this next step."
The former nursery - which covers about three acres - closed in 2016 for commercial reasons.
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