Guerilla gardeners have broken back into the community green they created after it was chained off by a security firm.

For the past month residents around Lewes Road, Brighton, have been enjoying the recreation space they carefully installed on the derelict site of a demolished Esso petrol station at the corner of Edinburgh Road.

They cleared rubble, laid a circular lawn, brought in benches, flower pots, sculptures and other decorations and planted flowers and shrubs into eyesore concrete blocks.

The site had previously been disused for five years but since it was spruced up during a series of "guerilla gardening days" it has been well used by residents.

They have taken responsibility for locking it each night and opening it in the morning.

Their activities had gone unchecked by the site's owners until Tuesday, when they arrived to discover a security firm had chained up the access gate and installed a warning sign to deter intruders.

Duncan Blinkhorn, a spokesman for the group behind the "Lewes Road Community Garden", yesterday said: "The gardeners were not so easily defeated and immediately set about lifting the gate off its hinges to allow continued access to the site."

The group also launched a petition which has been signed by more than 1,500 residents in two days.

It called for support to help keep the garden open and continue the good example of the community working together to beautify the area and create a facility from a derelict site.

King Sturge, the London-based property group acting on behalf of the site's owners, yesterday said the relevant member of staff was unavailable so it could not comment on why the gates had been chained or what it intended to do in future.

Gabriel Wulff, one of the garden organisers, said: "The point is we are not doing anything harmful to anyone. We are just providing a space for people to come together. We don't know what they meant by locking the site. We are not squatters, we are just using the site while it is available and will be happy to move it all if it is needed for use again."

Members of Brighton and Hove City Council said they would condemn any moves by the owners to stop the residents doing something "harmlessly good".

Councillor Keith Taylor, who represents that section of Lewes Road, is preparing to ask the council to negotiate with the owners for the land to be used.

Councillor Pat Hawkes, who represents the Hollingdean area where some of the gardeners live, said: "What they have done is beautiful. It's quite outrageous if security men are trying to secure it. It is quite harmless, it has been done with good intentions and is being used responsibly.

"It has raised the quality of life in the area and given a source of pride. I can't believe anyone would be as imbecilic as to try to stop it."

A link to the petition and dates of future community gardening days can be found in the Lewes Road Community Garden page on Facebook.