An international gathering of youth and children, billed as the largest ever of its type on climate change, on Thursday pressed world leaders to do far more to curb damage to the environment.

"We young people - three billion of the world population - are very concerned and frustrated that our governments are not doing enough to combat climate change ... we feel that radical and holistic measures are needed urgently from us all," they said in a statement following their conference in Deajeon in South Korea, itself one of the world's fastest growing polluters.

"We now need more actions and less talking."

Organised by the UN Environment Programme, the some-700 people from 10 to 24 years old and from dozens of countries met to discuss their concerns before the UN climate conference in December in Copenhagen.

That meeting will try to find an agreement to replace the Kyoto Protocol and set limits on emissions that are driving up global temperatures.

"We are the generation of tomorrow. The decisions that are made today will define our future and the world we have to live in. So we young people of the world urge governments to commit to a strong post-Kyoto climate regime. It is our lives we are talking about," UNEP quoted 23-year-old delegate Anne Walraven as saying.

The statement also urged governments to impose strict laws on polluters, develop independently-monitored carbon action plans and encourage greater use of green fuels.

"Make engaging environmental education mandatory in schools and universities and promote community environmental awareness - an informed public is a powerful public."

And they called on ordinary people to use alternative transport, pressure businesses to come up with environmentally-friendly products and push their own governments to act to improve the environment.

UNEP said they pledged to stage large rallies across 100 capitals to urge global leaders to take action on climate change under the UN Seal the Deal! campaign.