Large swaths of coastline – from Isles of Scilly to Wales and Scotland – are at risk of severe flooding, say forecasters

Britain will be battered by a fresh wave of "exceptional weather", with gale-force winds and driving rain creating a risk of widespread flooding, the environment secretary has warned.

Owen Paterson was speaking after a meeting of the government's Cobra committee on Thursday about the UK's flood response. He said emergency agencies and power companies were on high alert.

By Thursday night, the Environment Agency had issued a string of severe weather warnings – indicating threat to life and property – for coastal areas at the greatest risk of flooding.

Large swaths of the British coastline, from the Isles of Scilly to Wales and Scotland, were at risk of severe flooding, forecasters warned, as a further storm front was due to sweep in from the Atlantic on Friday and again on Sunday.

Pete Fox, head of strategy at the EA, said: "We are expecting flooding along the west and south coasts of England and Wales, due to a combination of strong winds, large waves and high tides, from the early hours of Friday and into the weekend.

"Coastal paths and promenades could be highly dangerous as there is an increased risk of being swept out to sea. People are warned to stay away from the shoreline."

Waves up to 9 metres high are set to crash into the coast of Cornwall and Devon on Friday, with 65mph winds creating hazardous conditions across seafronts.

The Police Service of Northern Ireland last night advised residents in part of east Belfast to pack their bags for possible evacuation amid fears of a tidal surge. High water and heavy rain is predicted for midday on Friday, Saturday and Sunday across Northern Ireland and officers asked members of the public to avoid coastal paths and to drive with extreme caution. High-risk areas include the densely packed residential streets of Sydenham and Victoria Park in east Belfast and around the docks.

The storm warnings came as a search for a 27-year-old man swept out to sea was called off after a body was found on Thursday morning at Porthleven Sands, Cornwall. The man, from Surrey, was swept off his feet in the sea while celebrating the new year with friends at Loe Bar.

A woman died in an accident along the coast, in Croyde, north Devon, after going swimming in the sea while on holiday with her family on New Year's Eve.

In Dorset, a search was under way for a man believed to have fallen into the River Stour, near Iford Bridge, Christchurch.

Paterson said ministers would make sure energy and transport companies were "absolutely prepared for the bad weather coming" to avoid the Christmas misery that left 150,000 homes without power and thousands of people struggling to get home.

"With a number of flood warnings in place today and more rain and high winds forecast for tomorrow, I have today chaired a Cobra meeting to make sure that across central government departments we are ensuring that local councils, utilities and transport companies are as prepared and ready to respond as possible," he said.

The EA said the flood risk extended along the coastline from north-west England, through Wales and south-west and southern England. Areas particularly at risk included the Isles of Scilly, the north and south coasts of Devon and Cornwall, Dorset and the Welsh coast.

There were severe weather warnings in place for the rivers Taw and Torridge on the Devonshire coast, where forecasters said that there would be flooding at numerous locations due to "high spring tides and significant surge combined with large waves from the south-west". Flood warnings were also in place in the Midlands, the north-west, Scotland and Northern Ireland. There were also 229 less serious flood alerts issued, covering most of the UK.

Another concern for emergency services were the gale-force winds, forecast to reach up to 60mph for west and south England on Friday, getting up to 50mph inland, including in London.

Forecasters expect to bring some respite, before another low-pressure weather front moves in from the Atlantic on Sunday.

Dan Williams, from the Met Office, said the danger was from the "strong winds combining with astronomical tides" along the coastlines. "The far bigger warning is for wind. We're talking about gale-force wind across the board for the UK. That means we've got strong winds that can push water around and big tides as well."

The worsening of the conditions prompted Devon and Cornwall police to warn people not to enter the sea or even walk along promenades.

A police spokeswoman said: "There are people who enjoy swimming in all weathers as well as those who may underestimate the danger a rough sea can pose. During the current bad weather we would appeal to everyone to use common sense and not put themselves in unnecessary danger.

"In addition, people who enjoy walking on beaches and rocky areas should take care not to allow themselves or their pets to get too close to waves."

The weather warnings come as firefighters in England and Wales prepared to stage a fresh strike Friday morning, concerned with their long-running dispute with the government over pensions. Members of the Fire Brigades Union will walk out for two hours at 6.30am, creating the ninth stoppage since September.

Under the terms of an agreement between the FBU, central government and fire services, strikers will return to work if there is a major emergency that could put large numbers of peopleat serious risk.