London, Feb 16 (AFP) A man died after falling into a river on Sunday as Storm Dennis swept across Britain with the army drafted in to help deal with heavy flooding and high winds.

The man fell into the River Tawe, in south Wales, police said.

"A male has fallen into the river at #Ystradgynlais at approximately 10am this morning and has sadly be found deceased further along the river in the Tebanos area," Dyfed Powys Police said in a tweet.

The government weather agency earlier issued a rare red warning for the area, saying there was a risk of "significant impacts from flooding" that included a "danger to life from fast flowing water, extensive flooding to property and road closures".

A record 594 flood warnings and alerts were in place on Sunday, extending from Scotland's River Tweed to Cornwall in southwest England.

Winds of over 90 miles per hour (150 kilometres per hour) were recorded in Aberdaron, south Wales.

Pictures circulated on social media showed the nearby River Taff bursting its banks, while rescue workers rushed to get people trapped in their homes in Powys to safety.

"The forecast is for very significant levels of rain, especially in the eastern valleys of South Wales," said Jeremy Parr, from government body Natural Resources Wales.

"Impacts could be severe overnight, and everyone should take the warnings extremely seriously," he added.

Police declared major incidents in parts of Wales and England, with landslides also reported.

"Some communities have been cut-off..., but emergency service workers are working tirelessly to put measures in place to ensure the safety of residents," South Wales Police said in a statement.

Roads and railways were badly affected by the downpours and winds, having barely recovered from a similar storm last week.

The Ministry of Defence deployed troops in West Yorkshire, northern England, which suffered badly from flooding caused by last weekend's Storm Ciara.

"Our armed forces are always ready to support local authorities and communities whenever they need it," said defence minister Ben Wallace.

British Airways and easyJet confirmed they had grounded flights, with footage posted online showing a massive Airbus A380 jet being blown about as it attempted to land.

Meanwhile, two bodies were pulled from rough seas off the south England coast on Saturday as the storm barrelled in.

One of the men is assumed to have been the subject of a search triggered when an LPG tanker reported that one of its crew was unaccounted for.

He was last seen several hours earlier.

Northwestern France was also affected by the storm, especially Britanny where the Finistere and Morbihan regions were placed on orange alert for rain and flooding, according to the national weather service, Meteo-France.

Around 14,000 homes were left without electricity.

"Winds will be increasing throughout the day on Sunday across Germany, Denmark and southern Sweden," said AccuWeather Meteorologist Maura Kelly. (AFP)

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