The advertising watchdog has mildly rebuked the government over the phrasing of a claim in two advertisements on the danger of climate change, while dismissing the rest of the complaints against the controversial television and newspaper campaign.

The campaign, run by the Department of Environment and Climate Change last winter, brought in 939 complaints. Various groups said the adverts were political, too scary, and factually misleading.

The vast majority of these complaints have now been dismissed by the authority.

The Advertising Standards Authority's only criticism was that a claim that "flooding, heat waves and storms will become more frequent and intense" should have be phrased more tentatively.

The environment secretary, Ed Miliband, said the authority had "comprehensively vindicated" the accuracy of the department's TV advert and had rebuffed those who attempted to use the advertising standards process to question the reality of man-made climate change.

"Science tells us it is more than 90% likely 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."