The famous meanders would be destroyed in the valley was flooded

It follows the decision by both Lewes and Wealden district councils to grant permission to an alternative scheme by local people to raise flood defences.

"The agency's plans cannot be bulldozed through given the disquiet at all levels," said Lewes MP Norman Baker.

A spokeswoman for the agency said it had not yet published any firm plans.

"We are not due to do so until the late autumn or winter so we cannot respond to a call by MPs for an inquiry into plans we have not yet published," she said.

Natural state

The valley, created in 1846, is an area of outstanding natural beauty and a site of special scientific interest.

The Environment Agency confirmed in 2003 it wanted to return the man-made valley to its natural state because of the erosion of its tidal banks.

It said its scheme would create a natural landscape rich with wildlife likely to attract more tourists.

But local people including Nigel Newton, chief executive of "Harry Potter" publishers Bloomsbury, have been fighting the plans since 2003.

Their alternative plan to raise the existing defences was approved by members of the two district councils against the advice of their officers.

Breaching the sea defences would allow salt marshes to form

"The agency's plans need to be tested in an independent forum, and if they are as scientifically sensible as it maintains, that process will validate them," said Mr Baker.

Nigel Waterson, MP for Eastbourne, said the valley's unique landscape and wildlife attracted 450,000 visitors a year.

"Nature cannot be allowed to take its course by flooding the valley without a full and transparent inquiry," he said.

The agency spokeswoman said it found it "incredible" that the alternative plan had been approved.

The defences could not be raised without the consent of landowners, East Sussex County Council and the National Trust.

"We are waiting to see what their response will be," she said.

"There is so much going on at the moment, it is difficult to know what the final outcome is going to be."