WASHINGTON -- U.S. Sen. Tom Coburn on Tuesday described as unacceptable a federal agency's unwillingness to explain why it denied individual assistance to Oklahoma victims of a January ice storm.

In a letter to Director David Paulison, the Oklahoma Republican also called on the Federal Emergency Management Agency to release all data it used in making that decision.

"I have traveled all across Oklahoma, received hundreds of letters, e-mails and phone calls, and I can tell you that confidence in FEMA has been shaken," Coburn wrote, suggesting that Paulison has encountered many of the same concerns elsewhere. "Only through complete transparency, and a willingness to explain all decisions in detail, will public confidence be restored."

He vowed to seek aggressive oversight of all agencies that fail to meet that mark.

Coburn spokesman Aaron Cooper said the senator hopes to fill in the blanks for Oklahomans as to why FEMA denied storm victims individual assistance rather than change that decision.

If FEMA fails to submit to the senator's request, Cooper said, a hearing would be among the possibilities.

Coburn serves on a Senate committee that has jurisdiction over FEMA.

He was chairman of a subcommittee that focused on financial management, but he lost that position when Democrats regained control of the Senate.

He reminded Paulison, however, that he remains the subcommittee's ranking member.

In early March, Oklahoma Gov. Brad Henry appealed the decision by FEMA to deny the state's request for individual assistance to storm victims in nine counties.

That appeal was turned down March 16, unleashing criticism from top Oklahoma officials.

They pointed out that FEMA's denial was inconsistent with past decisions regarding ice storms that caused similar damage.

In a March 7 letter to Paulison, members of the state's congressional delegation noted that the January ice storm had killed 32 people and left 3,079 others injured.

More than 125,000 homes and businesses lost power, and weeks after the storm, at least 4,000 remained without electricity, they wrote.

Coburn's April 9 letter to Paulison revives the issue that others thought was dead.

When asked about the timing of the senator's letter, Cooper said Coburn's office was being responsive to complaints it continues to receive from constituents and state officials.

"The fact that FEMA still hasn't released the information so far after the initial denial of assistance is a major concern," he said.

FEMA press secretary Aaron Walker would not comment on the specifics included in Co- burn's letter.

"I am not aware if the director has seen it as of yet," he said. "He has been out of the office."

Walker said any comment FEMA has would be given directly to Coburn, adding that the agency is always willing to work with members of Congress and help them understand its operation.

In announcing its decision to deny Henry's appeal, FEMA stated in March that it was standing by its initial finding that the private-sector impact in the nine counties was not of the severity and magnitude to warrant implementation of the individual assistance program.