HULL North MP Diana Johnson has branded a Government department "shambolic" after it mislaid 300 of her constituents letters.
On October 23, Ms Johnson was photographed delivering the letters to the Department for Environment, Food and Rural Affairs (Defra) in London.
However, earlier this week, Ms Johnson was told the office of Secretary of State Owen Paterson had lost the correspondence.
Residents had written to Ms Johnson describing their concerns at not being able to obtain reasonably-priced flood insurance.
On Thursday, she was told the letters had turned up – five weeks after they were delivered.
Ms Johnson said: "On Wednesday, Owen Paterson's private office told me the 300 letters that I delivered to Defra, addressed to him, had been lost.
"Now we are told that the letters have been found, five weeks after being delivered.
"This shambles is getting like an episode of In The Thick Of It, with Laurel and Hardy as special guest stars.
"All I want is for my constituents to be given a proper answer to their letter and hopefully one that gives them hope that they will be able to get flood insurance in future."
Ms Johnson said she is far from happy with the situation.
"The coalition Government's 27 per cent cut to flood defence funding is bad enough, but for 300 letters from Hull North constituents about the future of flood insurance to just be lost is unacceptable. It's a shambles."
Following the floods of summer 2007, many householders across East Yorkshire have the cost of insurance rocket.
Some residents have reportedly been unable to find an insurer willing to accept the risk of another "freak" storm.
Ms Johnson said: "The previous Defra Secretary told me in the Commons on June 25 that the Government had 'found a way forward with the insurance industry' and would make an announcement 'shortly'.
"Then we heard no more for several months. I then chased the issue up, to be told that negotiations between the Government and the insurance industry were unfinished."
A Defra spokesman said: "We have the letters. We will respond in due course."
