David Cameron has promised that "money is no object" in providing relief to communities affected by floods, as he warned that the country faces "a long haul" to recover from the devastation of recent weeks.
Fresh from a two-day tour of inundated communities in South-West England and the Thames Valley, the Prime Minister announced he was cancelling a planned trip to the Middle East to take personal charge of the relief operation.
With 16 severe flood warnings, 133 flood warnings and 225 flood alerts still in force, he told a Downing Street news conference that the situation could deteriorate further.
"There is absolutely no sign of this threat abating, and with further rain and strong winds forecast throughout the week, things may get worse before they get better," he said.
Mr Cameron's warning came as the Environment Agency (EA) said rises in the level of the River Thames were set to cause more disruption for flood-hit areas.
Around 1,000 properties have been reported as flooded in the past week, including 800 along the Thames, and the EA said that Windsor and Maidenhead, in Berkshire, as well as parts of Surrey were now at risk . Since the beginning of December, a total of 5,800 premises have been flooded and more than 1.3 million protected by flood schemes, said the Agency.
EA senior flood adviser Kate Marks warned it was "increasingly likely" that there would also be problems along the River Severn and River Wye.
And the Met Office forecast 20-40mm (0.75-1.5 inches) of rain by Friday night across many southern and western areas, with as much as 70mm (2.75 inches) in the already sodden West Country, south Wales, western Scotland and Northern Ireland.
A storm due to hit tomorrow could fell trees and cause transport and power disruption, with winds in the South West potentially reaching 80mph. And there is continuing disruption to rail services in the Thames Valley and West Country.
About 100 properties remain flooded on the Somerset Levels, where extra pumps are being brought in from the Netherlands, and groun dwater flooding is also expected in the coming days in Hampshire, Kent and parts of London. The Thames barrier closed again this morning to protect communities to the West of the capital.
Announcing new support for householders, businesses and farms, Mr Cameron said every effort would be made to help affected areas get back on their feet.
"Money is no object in this relief effort. Whatever money is needed for it will be spent," he said.
The Prime Minister was this evening leading a meeting of the Government's emergency committee Cobra in Whitehall to assess the latest situation, and on Thursday he will chair a new Cabinet committee set up to oversee the recovery.
He said a tax deferral scheme will help businesses hit by flooding, while up to £10 million in new funding is being found to support farmers. Grants of several thousand pounds for homeowners and businesses will be available to improve flood defences as they repair their properties.
The PM rejected calls to divert funds from the overseas aid budget to the flood relief effort, insisting that, as a "wealthy country with a growing economy" Britain does not have to choose between the two.
Some 1,600 troops have now been deployed to assist with flood protection and relief, and the Prime Minister said that "thousands more" were available for tasks like filling and mov ing sandbags, getting medical assistance to the sick and helping vulnerable people. Appointing Major General Patrick Sanders to co-ordinate the military response, he said local authorities should not think twice before calling on the resources of the armed forces.
Labour leader Ed Miliband called on ministers to ensure insurance is paid promptly and protect access to insurance in future for people in flood-hit areas.
Speaking after a visit to flooded areas of Berkshire, Mr Miliband said: "The Government should be getting round the table with the insurance industry immediately to ensure every firm is signed up to clear principles of prompt assessment and payment. Now is not the time for foot-dragging of the kind we saw after the riots."
Insurers and business organisations met in Downing Street to speed up the response to claims from flood-hit companies. And Mr Cameron said that householders who experience difficulties with insurance should tell their local MPs, so the authorities can "go after those insurance companies and make sure they pay up". Local authorities will be able to request top-ups from central government for hardship funds for those with no insurance.
Mr Cameron acknowledged that it would take a "depressingly long period of time" for the country to get back to normal.
Repairs to the seafront rail link at Dawlish in Devon were expected to take six weeks, while pumping the water from the Somerset levels would take "a lot of time" even if there was no more rain. Even after water levels drop, householders face a "really painful and depressing process" of restoring their homes and replacing furniture, said the Prime Minister.
"It will be a long haul and it will require a stepped-up national effort with the whole country pulling together," he said.
Mr Cameron hailed the "inspiring" volunteers who have shown "the best of Britain" by stepping forward to help their communities.
And he praised the work of the Environment Agency's staff for the "brilliant job" they have done on the ground, but again offered only limited support for its under-fire chairman Lord Smith.
"Of course there will be a time to discuss how the pendulum against dredging swung too far in the past and how we put that right in the future," said the Prime Minister.
"But right now everybody needs every minister, every head of an agency, everyone involved, to work together to deliver the best possible response we can to these floods and that is exactly what is happening... Now is not the time for resignations."
Mr Cameron defended the Government's record of investing in flood defences, but admitted: "The truth is that when you have these extraordinary weather events, the wettest winter for 250 years, it is very difficult to have all the protections in place that you need".
Even those who were sceptical about man-made global warming should recognise the need for action to make the country more resilient in the face of the "challenges of extreme weather".
"Whether you think this is linked to climate change or whether you don't think it's linked to climate change, we should all unite in a great national effort to deal with these problems and to address them head-on and make our country more resilient because, whatever our views, it's clearly in the interests of everyone in our country," he said.
The GMB union, which represents staff at the Environment Agency, said it has learned that most of the £130 million additional funding announced by the Government in response to the crisis will be spent on capital projects, saving few - if any - of the 1,700 jobs under threat due to budget cuts.