Britain's advertising watchdog has banned two government adverts for overstating the threat from climate change, it said on Wednesday.

The adverts used nursery rhymes including "Jack and Jill" to highlight the impact of global warming, but the Advertising Standards Authority (ASA) said they exaggerated the risk.

"Jack and Jill went up the hill to fetch a pail of water. There was none as extreme weather due to climate change had caused a drought," read the copyline on one of the ads.

"Extreme weather conditions such as flooding, heat waves and storms will become more frequent and intense," warned the advert, commissioned by the Department of Energy and Climate Change (DECC).

The second advert read: "Rub-a-dub-dub, three men in a tub -- a necessary course of action due to flash flooding caused by climate change."

"Climate change is happening. Temperature and sea levels are rising. Extreme weather events such as storms, floods and heat waves will become more frequent and intense," it said.

And it warned: "If we carry on at this rate, life in 25 years could be very different."

The adverts were part of a DECC campaign last year which attracted 939 complaints.

Upholding the complaints, the ASA said that forecasts by the Intergovernmental Panel on Climate Change (IPCC) "involved uncertainties" that the adverts failed to reflect.

Energy and Climate Change Secretary Ed Miliband downplayed the problem raised by the ASA.

"The science tells us that it is more than 90 percent likely that there will be more extreme weather events if we don't act. In any future campaign, as requested by the ASA, we will make clear the nature of this prediction.

"We will continue to provide public information about the dangers of climate change," he added.