Under-fire Environment Agency boss Lord Smith has accused ministers of "getting in the way" of vital work to deal with devastating floods by turning the crisis into a political row.
The peer hit back at criticism of his and the quango's handling of the situation and pointed the finger of blame for the failure to sufficiently dredge rivers at Treasury funding rules.
Communities Secretary Eric Pickles has blamed faulty Agency advice for the scale of the damage to the Somerset Levels and declined to dismiss calls for the former Labour cabinet minister to resign.
"We made a mistake, there's no doubt about that and we perhaps relied too much on the Environment Agency's advice," Mr Pickles told BBC1's Andrew Marr Show.
"I am really sorry that we took the advice ... we thought we were dealing with experts."
Politicians including David Cameron have been visiting the worst affected areas in the south west as efforts are made to restore transport and power and get people back into their homes.
With more severe weather expected over the coming days, there are now 16 severe flood warnings in place - meaning a risk to life - as more areas brace for rising waters, notably the Thames Valley.
Lord Smith - who faced the ire of locals when he did not apologise for the EA's performance when he was besieged during his own visit to the Levels - said his "heart goes out" to all the victims.
He accepted there was " always more that we can do" and welcomed a £130 million Government funding boost for repairs.
But he issued a furious broadside at what he said were attempts by politicians to undermine the work and reputation of the Agency in a bid to secure better media coverage.
"What really saddens me, though, is seeing the Environment Agency's work and expertise in flood-risk management, internationally respected and locally praised in many parts of the country, being used as a political football for a good media story," he wrote in an article for the Guardian.
"In a lifetime in public life, I've never seen the same sort of storm of background briefing, personal sniping and media frenzy getting in the way of decent people doing a valiant job trying to cope with unprecedented natural forces.
"Our staff have worked their hearts out in order to protect as many people as possible in the face of extreme weather.
"They'll carry on doing so. But there's no place for playing politics in the serious business of flood protection."
He said a Treasury-imposed "benefit-to-cost" rule had limited the sum the EA had been able to devote to dredging the silted-up rivers which failed to drain the Levels properly.
It had put the maximum £400,000 on the table it was allowed to, he said, but "t he additional funds from other sources that would be needed didn't come in".
"So when politicians start saying it's Environment Agency advice or decisions that are to blame, they need to realise that it's in fact government rules - laid down by successive governments, Labour and Tory - that are at the heart of the problem."
Repeated calls for dredging were made to Downing Street and other Whitehall departments by farmers and others in the region from at least six months ago but funding was declined.
Mr Pickles - who has taken the lead while Environment Secretary Owen Paterson recovers from eye surgery - earlier said the agency needed to revisit its priorities.
As politicians traded blows on the political fall-out from the disaster, police were investigating whether seven-year-old Zane Gbangbola, who died after falling ill in his flood-hit home in Chertsey, Surrey, may have become a victim of the floods.
Officers have refused to be drawn on whether carbon monoxide poisoning from a generator pumping out flood water from his home may have been to blame, which also saw his parents, Kye Gbangbola and Nicole Lawler, taken ill.
The Prime Minister, speaking after chairing a meeting of the Government's Cobra emergency committee this evening, said he had " made clear again that every resource is available to the local communities affected.
"We will keep providing whatever immediate practical support and assistance is needed, whether that is extra pumps and sandbags; military support on the ground; emergency funds from the new £7 million severe weather assistance fund for local councils.
"In Somerset, the Environment Agency is starting a further flood alleviation plan and, as I've said before, when the water levels come down and it's safe to do so, they will be dredging to make sure that these rivers and ditches can carry more water."
Network Rail had been told to do " whatever it takes" to restore badly disrupted rail links - which earlier saw the south west cut off entirely.
Rail operators are now able to run trains to Exeter but there is still major disruption to services following flooding, landslides and collapsing track beds in the West Country.
"I want to assure the public and communities affected that we are doing all we can to get them back on their feet," Mr Cameron said.
Heavy rain and winds of more than 60mph will die down throughout today but the brief respite will be broken by another storm arriving tomorrow night.
There are nearly 300 low-level flood alerts and almost 200 medium-risk warnings in place across Wales and central and southern England.
The Met Office warned that river levels are expected to continue rising along the Thames, the Severn and the Dorset Stour this week.
The Ministry of Defence has put 1,600 personnel on six hours' notice to help in the south.
Of the severe flood warnings, 14 relate to a lengthy stretch of the Thames - which Mr Pickles said was expected to suffer "significant" problems by the middle of the week.
The Agency said they stretched "from Datchet to Shepperton Green, including Ham Court and Chertsey, as river levels in the area are extremely high and are forecast to continue to rise".
A further 20,000 sandbags are ready to be deployed to communities at risk of flooding on the Somerset Levels.
Somerset County Council staff have worked tirelessly alongside Royal Marines from 40 Commando throughout the weekend to prepare a further 20,000 sandbags for use.
Council leader John Osman, said: "Our main aim is to keep residents and their property as safe as possible.
"These additional 20,000 sandbags will help towards these efforts. Floodwater is still rising and more than 150 homes are at risk of flooding in Somerset.
"We are working tirelessly 24/7 to ensure residents are safe, our roads are as clear as they can be in these difficult circumstances, schools are open, school buses can operate and vulnerable people receive the care and services they need."
A Ministry of Defence spokesman said: "Military personnel, currently mostly Royal Marines, continue to provide support in Somerset in areas affected by floods as part of cross-Government and multi-agency relief efforts.
"As the Prime Minister has said, all available resources are being brought to bear to help those still struggling as a result of the floods."