A former landfill area being considered as a travellers' site has been closed because of high levels of toxic gases.

Brighton and Hove City Council has cordoned off parts of Sheepcote Valley in east Brighton following advice from the Environment Agency.

Campaigners who oppose the travellers' site on health and safety grounds say people who move on to the land could be exposed to an increased risk of developing cancers.

In a letter addressed to East Brighton ward councillors, Ben Seller, the council's Cityclean and Citypark's officer, said Sheepcote Valley will be closed from July 8 to 18 due to rising gas levels.

"Data has been supplied to specialists at the Environment Agency for their comment.

"The agency has suggested as a precautionary measure that we should temporarily close the site due to the potentially toxic and explosive nature of some of the gases.

"The concentration of the gases has risen, which has caused concern but the risk to human health remains low.

"The medium and longterm requirements may include keeping the site closed to the public and remedial work to aid the natural release of the gases."

Sheepcote Valley, which was a landfill site until 1979, is one of several sites being considered for the city's first permanent travellers' site.

East Brighton councillor Gill Mitchell said: "This makes it even more incomprehensible that the area is being considered.

"I have never known the site to be closed before for this reason."

June Evans, chairwoman of conservation group Friends of Sheepcote Valley, said: "It seems strange the council has closed the site unless there are high methane levels.

"The area hasn't been closed to the public since it opened about ten years ago.

"People have been saying recently they have been able to smell the methane in the air."

A Brighton and Hove City Council spokeswoman said: "An area formerly used for landfill has been temporarily closed while routine tests are carried out.

"This is standard practice in former landfill sites and the council is following national guidelines."

The council said the tests were not part of an assessment to determine if the site was suitable for travellers.