They've been a popular stunt for charities and schools for decades, but now officials want to burst their balloon.

Councillors have agreed to try to persuade people to stop mass balloon launches because of fears at what the rubber does to wildlife - and they may even ban it across the city.

Former Lord Mayor Ann Spokes Symonds won the change this week, after campaigning against balloon launches for eight years.

She said: "I don't want to be a spoilsport. It's just these mass releases of hundreds and thousands of balloons into the air.

"Some come down quite near but some go many, many miles. Wherever they land, they are a danger because animals think they are food."

Mrs Spokes Symonds said the balloons could block an animal's gut, causing it to starve to death.

She added: "Turtles particularly think they are jellyfish and eat them. Birds also get tangled in the strings that are attached to balloons."

The move left John Newman - who recently helped raise more than £700 for Oxford's Helen and Douglas House hospices with a balloon race - deflated.

Mr Newman, manager at the Snakes and Ladders Play Centre in Abingdon, said: "I think it's ridiculous. I would not be in favour of banning it. It raises lots of money.

"We would not want to stop it but if there was a code of conduct, we could follow that."

The council's environment scrutiny committee agreed to promote the Marine Conservation Society's balloon guidelines, which encourage groups to organise balloon popping competitions or balloon sculptures instead of releasing them into the sky.

It also calls for people to use balloons made of natural rubber and filled with air, not helium.

Councillor Mary Clarkson told the committee: "Lots of people are simply unaware of the dangers. One of the most important things we can do is promote this code of conduct."

But Lord Mayor John Tanner said the council should lead by example.

He said: "The first step is saying we should not allow balloons to be released from our own land or by our officers. The second is looking at a by-law for a total ban.

"There are all sorts of ways of raising money or making a point. You don't need to let off balloons."

The committee has asked officers to look at a ban. One city charity has agreed to abide by it.

Nikki Barber, spokesman for Helen and Douglas House hospices, said: "We will be advising all our supporters to think of different ways to raise awareness for fundraising events as protecting the wildlife and the natural landscape is hugely important."

South Hams District Council and Shetland Islands Council have already banned mass balloon releases.