Critics of Bristol City Council's plan to sell green spaces have claimed the authority has broken its own pledge on the scheme.

In December the Liberal Democrat cabinet approved the sale of more than 40 of the city's green spaces despite public opposition.

But residents believe they have overlooked a significant clause in the Parks and Green Spaces Strategy (PGSS) that was agreed by all parties in February, 2008.

Selling up to 64 sites was supposed to raise £41 million towards the £87 million parks improvements plan, which aims to upgrade green spaces in Bristol over the next 17 years after decades of low investment.

The rest of the money would come from developers' contributions, the parks budget and grant funding.

Now the council only expects to raise £11 million from the sales after nine sites were saved from developers after public outcry, and the decline in land values since 2006 estimates. This means the council is £30 million short.

A clause in the original PGSS suggests this dramatic change in funding should have forced the council to review the plan and find other ways of paying for it.

It states: "It is important to emphasise that it is not the council's intention to keep selling land until the funding requirements of the strategy are achieved, irrespective of the importance and 'value' of the space to the community.

"On the contrary, should there be insufficient 'low value' marginal land available once the area planning process has been concluded, the council will review the ambitions of the strategy and consider alternate funding sources."

Residents who have highlighted this claim to have been ignored.

Pete Goodwin, of Friends of Stockwood Open Spaces, highlighted the passage in his group's submission during the consultation process, but it was initially "lost" and not included in the final officers' report on the issue.

He said: "We've said right through that the funding must be reviewed, as provided for in the strategy, but we've been ignored.

"It makes you wonder why some parts of the strategy are treated as binding, while other parts can be ignored."

Alison Devonshire, of Friends of Okebourne, said: "They need to be brought to book over this. I have complained on 'have your say' on the council website and I would urge everyone to do the same as the consultation has in fact been used as a tick box, and has not taken the views of the public into consideration."

Rosemarie Rendu-Jefferies, of Lodge Hill, said: "We will end up losing our precious green spaces for a plan which will not fulfil the objective. The whole thing makes no sense."

Council leader Barbara Janke said: "We have recently reviewed the original, 2008 decision by looking again at the proposals and withdrawing some of the sites we were being recommended to put on the market.

"This is a 20-year strategy and, clearly, over the period land values are likely to change and we cannot now predict the proceeds of site sales.

"Funds will be coming from other sources as well and the final objectives, such as play parks and other improvements, will be determined by the limits of the funds available.

"Can we be quite clear that, without a strategy, it would not be possible to allocate funds for improvements to our city's parks and open spaces. With the strategy in place, funds from a variety of sources – including, for instance, section 106 funding from private developers – can now be allocated."

How the money will be spent will be determined by Neighbourhood Partnerships.

Over the past three weeks the Evening Post has looked in detail at the record number of responses to the green spaces plan received by the council last year.

In the majority of cases, it would appear residents often want the cheapest and simplest improvements for their parks.