(CNN) -- A Democratic congressman from Mississippi plans to hold a hearing into how millions of dollars worth of supplies meant for Gulf Coast hurricane survivors ended up being given away as surplus property.

Rep. Bennie Thompson says he'll hold a hearing into how supplies for Katrina victims were diverted.

Rep. Bennie Thompson, chairman of the House Committee on Homeland Security, called the situation "a debacle."

In June, CNN revealed that the Federal Emergency Management Agency had warehoused $85 million worth of household goods for two years before giving them away to federal agencies and 16 states. But Thompson said there is still a great need for basic supplies in Mississippi.

"We just think that FEMA needs to come and tell the committee how such a debacle could occur, and in the process, what are they going to do to assure Congress and the taxpaying public that it will never happen again," Thompson said.

The household goods were meant to help Gulf Coast households rebuild. But they sat in FEMA warehouses for two years before the agency declared them surplus property and gave them away in February.

The state of Louisiana had not asked for any of the supplies, prompting outrage there after the original CNN report. Since then, the state has taken steps to claim some of the stockpiles and distribute them to groups working to resettle victims of Hurricane Katrina, the 2005 storm that flooded New Orleans and ravaged the Mississippi Gulf Coast.

Mississippi took the supplies it was offered but did not give them to Katrina victims. Instead, as CNN reported this week, the state distributed them to prisons, volunteer fire departments, colleges and other state agencies.

Thompson said he was stunned at how Mississippi officials made "a mockery of the whole process."

"I'm disappointed that my state decided that prisoners had a higher priority than Katrina victims and has made no effort to correct it even when this mistake was made," he said.

"Any time items intended for victims of Katrina end up in the hands of the Department of Corrections or state employees, then clearly, Mississippi dropped the ball." Watch victims tell why they need the items »

Thompson said his committee would "ask all the tough questions" and demand any documents associated with the matter.

"So we are prepared, if necessary, to put those officials under oath," he said. "We are prepared if necessary to subpoena any and all documents relative to this situation."

FEMA spokesman Marty Bahamonde said the agency welcomed any congressional hearing.

"We always make ourselves available to answer the questions. That's something we are always ready to do," he said.

FEMA said it was costing more than $1 million a year to store the supplies, but officials have not been able to answer why the agency didn't get the supplies to Katrina victims. FEMA said the agency has launched an internal probe into the issue.

Jim Marler, director of Mississippi's surplus agency, failed to return repeated phone calls over several months to explain what happened there. But spokeswoman Kym Wiggins said the agency was not told the items were still needed -- a statement that didn't sit well with groups working to rebuild the stricken coast.

Bill Stallworth, executive director of the Hope Coordination Center in Biloxi, said he and other community leaders would have begged for the FEMA stockpiles had they known they were available.

"When I hear people stand up and just beat their chest and say we've got everything under control, that's when I just want to slap them upside the head and say, 'Get a grip, get a life,' " said Stallworth, also a Biloxi city councilman.

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