Families of those killed in the attacks of Sept. 11, 2001 said Thursday that excessive secrecy by the government is keeping from them what went wrong before the hijackings.

"All we want is the truth," said Michael Low of Batesville, Ark., whose daughter Sara was a flight attendant on one of the airplanes that flew into the World Trade Center. "We believe in freedom and open government, but at times it seems like we're getting the old Soviet Union."

A handful of family members held a news conference in the Capitol to push for a law that would unlock secrets kept by the Transportation Security Administration.

The TSA was given broad authority to protect sensitive security information — known as SSI — when it took over transportation security after the attacks.

The families are especially angry that the TSA refuses to give them information that was given to the lawyers for convicted Sept. 11 conspirator Zacarias Moussaoui, including about 150,000 FBI interviews of witnesses and several thousand CDs.

During Moussaoui's trial, U.S. District Judge Leonie Brinkema twice ordered the government to turn over the information to the families.

"It's quite extraordinary that TSA has a tougher policy on disclosure than the CIA or the FBI or the NSA (National Security Agency)," Brinkema said.

TSA spokeswoman Yolanda Clark said the agency is cooperating. It just gave the families' lawyers the operations guide for security checkpoints, and they were about to get the aircraft standard security program, she said. Both date to before the attacks.

"TSA has always been sensitive to the Sept. 11 families' issues," Clark said. "But we've determined that the public and transportation security as a whole are best served by limited access to information."

Information that needs to be kept secret, she said, includes:

— How TSA selects airline passengers for random screening.

— The vulnerability of important tunnels to terrorist attack.

— How bomb-detection machinery works and how it can be contaminated.

"We hold close those things that need to be kept close," Clark said.

Some of the families are hoping to get information about security standards before Sept. 11 because they are bringing a negligence suit against American and United airlines, which operated the hijacked airlines. Others just want more oversight of the TSA.

"Without accountability we are going to revisit another 9/11 sooner than we think," said Hamilton Peterson, whose father and stepmother died on Flight 93 when it crashed in a field in Pennsylvania.

Democratic Rep. Martin Sabo of Minnesota said TSA's unique secretiveness makes it hard for Congress to oversee the agency.

"It's been a constant problem," Sabo said. "There was no process within TSA. Virtually anyone could classify."

Sabo and Republican Rep. Harold Rogers of Kentucky persuaded the House to adopt a requirement that the Homeland Security Department, of which TSA is part, release all security information that's more than three years old, if it's not part of an existing security plan.

The Sabo-Rogers measure would also require the TSA to turn over documents requested by a judge in a legal proceeding unless the agency can demonstrate why it shouldn't.

The Sept. 11 families, during their news conference, urged the Senate to approve the requirements for more openness from the TSA.

Clark said the Senate shouldn't agree to require the TSA to turn over documents if a judge requests them.

"They might as well write a provision that says there is no longer sensitive security information," she said. Government wouldn't be able to keep any secrets, she said, because they could all be related to litigation.

Clark also said the TSA has improved its system for designating information "sensitive."

"It's a completely different office than it was one year ago," she said. "It's not the first thing you do when you're trying to keep another 9/11 from happening."