Around 6.3 million homes and businesses are located in areas at risk of flooding from one or a combination of rivers, the sea and surface water, up from 5.5 million when the last assessment was conducted in 2018.

"With climate change, the total number of properties in areas at risk from rivers and the sea or surface water could increase to around 8 million by the middle of the century -- or around one in four properties," said the agency, which is tasked by the government with flood management.

The models, published as the country cleans up from deadly storms Bert and Darragh, use "cutting-edge" methods that integrate detailed local data, such as new buildings, to make the predictions.

For the first time, they also account for the latest UK climate projections from the Met Office.

The assessments will be used by the government, Environment Agency and local communities to improve flood resilience.

Around 4.6 million of the identified properties are at risk from flash flooding, where rainwater overwhelms drainage systems, a 43 percent increase since the 2018 assessment.

"These changes are almost entirely due to significant improvements in the Environment Agency's data, modelling and use of technology providing a more accurate assessment of surface water flood risk," said the agency.

Around 2.4 million properties are in areas at risk of flooding from rivers and the sea.

The updated assessment also showed that 3,500 properties are expected to be in areas at risk of coastal erosion in the period up to 2055, increasing to about 10,100 properties by the end of the century.

"More detailed flood and coastal risk information, which takes climate change into account, is essential for local authorities to be able to plan effectively, to protect their local communities," said Hannah Bartram, from the Association of Directors for Environment, Planning and Transport.

As global temperatures rise because of climate change, scientists have warned that heatwaves and other extreme weather events, such as severe flooding, droughts and wildfires will become more frequent and more intense.