Climate change did not cause the devastating floods that hit northern England last August, a report said on Tuesday.

They were an exceptional event that statistically might occur every 100 to 200 years and not part of any discernible trend, said Terry Marsh and Jamie Hannaford of the Centre for Ecology and Hydrology.

"The river floods of Summer 2007 were a very singular episode, which does not form part of any clear historical trend or show consistency with currently favoured climate change scenarios," Marsh said

"Long historical flood records show no compelling long term increase in flood magnitude," he added.

The floods caused some three billion pounds worth of damage and prompted speculation that they were further proof of climate change which is predicted to cause more extreme weather events as well as longer, drier Summers and warmer, wetter Winters.

But the pair pointed out that the ground, which in Summer would normally be dry and capable of absorbing large amounts of water, was already saturated after the abnormally high rainfall between May and July.

The report, "The Summer 2007 floods in England and Wales - a hydrological appraisal" said there was no close modern parallel for last Summer's floods.

Marsh said that while records showed that temperature changes had moved outside the historical range, the same was not true of river flows and therefore the floods could not be attributed to global warming.

But he warned that while flood management systems had by and large performed to their design limits, which could cope with the normal range of events, vulnerability to flooding was rising because of urban developments increasingly being built on flood plains.

The report found that heavy rainfall led to severe flooding in many river basins including the Thames and the Severn, and that in some areas the flooding was more severe than in 1947 - the worst floods in England and Wales last century.

The report said the 2007 flooding "underlined the UK's continuing vulnerability to climatic extremes but long-term rainfall and river flow records confirm the exceptional rarity of the hydrological conditions experienced in 2007.