Most of New Orleans was flooded in the aftermath of the storm

They show Federal Emergency Management Agency (Fema) officials scrambling for supplies and personnel.

Fema's then-head, Michael Brown, at one point seemed not be aware that the agency was evacuating storm victims.

The e-mails were requested by the committee investigating the crisis, and obtained by the AP news agency.

Michael Chertoff, the head of the Department of Homeland Security - of which Fema is a branch - is to appear in front of the congressional panel on Wednesday.

Mr Brown appeared before the panel last month.

Hurricane Katrina devastated parts of Louisiana and Mississippi on 29 August, killing about 1,200 people.

'All you can send'

The e-mails show that the government's hurricane response plan ran into difficulties even before the storm hit the Louisiana coastline.

Mr Brown's deputy chief of staff, Brooks Altshuler, complained in an e-mail about White House pressure to form an interagency crisis management group, which was a key part of the plan.

"None of them have [sic] a clue about emergency management or economic impacts for that matter," he wrote.

Michael Brown resigned amid mounting criticism

After the storm hit, the problems continued.

Then-Fema recovery co-ordinator William Carwile wrote to a state official: "Biggest issue: resources are far exceeded by requirements... Getting less than 25% of what we have been requesting from HQ daily."

Mr Carwile also e-mailed Florida officials, begging for relief aid.

"Food is also critical. Need MRE [ready-to-eat meals] and/or heater meals if you have any. Water, ice, food in eastern counties should be your priority... Also know FL [Florida] is providing law enforcement. Need all you can send."

Five days after the storm, Mr Brown - who resigned in the wake of the crisis - e-mailed an aide, saying that there had been "no action from us" to evacuate storm victims.

Less than 30 minutes later, Fema deputy operations director Michael Lowder replied: "This is flat wrong. We have been flying planes all afternoon and evening."

Earlier, a Fema official in Mississippi received an e-mail asking for Mr Brown's satellite telephone number so that a senior military official could call him.

"Not here in MS [Mississippi]. Is in LA [Louisiana] as far as I know," Mr Carwile replied.