WASHINGTON - Federal agencies are struggling to keep up with the growing number of requests for public information, raising questions in Congress about the Obama administration's dedication to transparency.

The backlog of unfulfilled requests for documents has doubled since President Barack Obama took office in 2009, according to a recent report by the Justice Department. The number of requests also has spiked.

"The president has committed to creating an unprecedented level of openness in government," said Rep. Jason Chaffetz, R-Utah, chairman of the House Oversight and Government Reform Committee. "But that's not the case" in filling requests under the Freedom of Information Act.

Chaffetz cited examples of people waiting years for documents only to have their requests denied. In other cases, federal agencies blacked out information that was public elsewhere. One document produced by the Federal Communications Commission blacked out a news release already publicly released, Chaffetz said.

Chaffetz' committee wrapped up two days of hearings on the FOIA Wednesday, with some Republican members chastising federal officials responsible for disclosing public information.

"You're part of the problem," said Rep. Jody Hice, R-Ga.

Officials from the Departments of State, Justice, Homeland Security and Treasury testified, along with an official from the IRS.

Several Democrats came to their defense, noting that budget cuts have left fewer workers to process information requests.

"Logic tells you that when you have less people and you've got more demand, you're going to have problems," said Rep. Elijah Cummings of Maryland, the committee's top Democrat.

Governmentwide, the backlog of requests went from 77,000 in 2009 to nearly 160,000 in 2014, according to the Justice Department report.

The increase coincided with a jump in requests. In 2009, the federal government received almost 558,000 requests for information. In 2014, the number increased to more than 714,000.

At the same time, the number of staff working full time on information requests dropped from a high of 4,400 in 2011 to about 3,800 in 2014.