Senators on Wednesday demanded to know whether President Bush's mine safety chief could have done more to prevent a deadly coal mine collapse in Utah.

"This Congress has given the administration the resources and technology it needs" to make mines safer, said Sen. Tom Harkin, D-Iowa, chairman of the Senate Appropriations subcommittee that oversees mine safety.

"Well, what happened?" Harkin asked, at the first hearing since the Aug. 6 disaster at Crandall Canyon Mine.

Nine miners died because of the collapse, which left six of its victims entombed.

Mine safety chief Richard Stickler was to answer their questions later at the hearing. Others to testify included President Clinton's mine safety director, Davitt McAteer. Senators had invited testimony from Robert Murray, the Crandall Canyon Mine's co-owner, but Senate staffers said Tuesday that Murray declined to appear.

Senators are skeptical that Stickler's agency is doing enough to enforce mine safety rules. Before the Utah collapse, there were the disasters last year at West Virginia's Sago mine and two others. The three accidents helped make 2006 the deadliest year for coal mining in more than a decade.

Senators want to know whether more regulations are necessary and if the safety improvements mandated after Sago are being put in place fast enough.

"What the hell does it take to shake up that agency?" Sen. Robert Byrd, D-W.Va., said Tuesday.

"MSHA was intended to be a strong federal agency with the authority to investigate, penalize and, when necessary, shut down a coal mine for safety violations," Byrd said. "It is infuriating to watch MSHA, even after the tragedy at Sago, continue its tepid minimalist approach to mine safety."

Six miners were trapped when the Utah mine collapsed with such force that it felt like an earthquake. Ten days later, three rescue workers were killed when the mine caved in again.

Last week, MSHA called off attempts to find the miners by drilling holes from the surface after a seventh hole found no signs of life. It ended a gut-wrenching month in which experts, union officials and family members have questioned MSHA's judgment about the mine plan and the rescue efforts.

Several congressional panels are investigating MSHA's role at Crandall Canyon, among other aspects of the accident. More hearings are expected in October.

Congress moved quickly to pass a flurry of laws after last year's deadly accidents. They called for the government to develop new communications equipment by 2009 that could survive the force of a massive cave-in and lead rescuers to trapped miners.