The embattled chief executive of Massey Energy accused federal regulators Tuesday of not making a genuine effort to investigate the explosion that killed 29 miners and injured two at the company's Upper Big Branch mine in West Virginia.

Instead, the Mine Safety and Health Administration is lying to the public in hopes of winning a publicity battle, Don Blankenship told an industry conference.

"Today what you have is MSHAgate. You've got a situation where they won't tell the truth about what they know,'' he said. "We're not making a genuine effort at the government level to find out what happened.

He said more must be done to prevent explosions, but with the realization that not every blast is avoidable.

An MSHA spokeswoman did not immediately respond to an e-mail requesting comment Tuesday evening.

The agency is heading the civil investigation into the April 5 explosion, the worst U.S. coal mining disaster in 40 years. The U.S. Department of Justice is overseeing a separate criminal investigation.

Earlier in the day, MSHA announced an emergency rule to require underground mines to do more to control explosive coal dust following the deadliest U.S. coal mine explosion in 40 years. It's first major federal regulatory change since the disaster.

The change comes after growing evidence that coal dust played a role in the blast explosion.

The change will increase the amount of pulverized stone or other inert material that mines must use to dilute coal dust in tunnels that bring fresh air underground.

The change is based on federal research that shows decreasing the amount of coal dust in air intakes can help prevent explosions, Main said.

Mines must comply by Oct. 7 in new areas and by Nov. 22 in existing tunnels, Main said.

The coal industry expressed immediate support for the change, which is already a state requirement in West Virginia.

"West Virginia producers are complying,'' said Luke Popovich, a spokesman for the National Mining Association. "Many have carried it to their operations outside West Virginia.''

Instead, the Mine Safety and Health Administration is lying to the public in hopes of winning a publicity battle, Don Blankenship told an industry conference.

"Today what you have is MSHAgate. You've got a situation where they won't tell the truth about what they know,'' he said. "We're not making a genuine effort at the government level to find out what happened.

He said more must be done to prevent explosions, but with the realization that not every blast is avoidable.

An MSHA spokeswoman did not immediately respond to an e-mail requesting comment Tuesday evening.

The agency is heading the civil investigation into the April 5 explosion, the worst U.S. coal mining disaster in 40 years. The U.S. Department of Justice is overseeing a separate criminal investigation.

Earlier in the day, MSHA announced an emergency rule to require underground mines to do more to control explosive coal dust following the deadliest U.S. coal mine explosion in 40 years. It's first major federal regulatory change since the disaster.

The change comes after growing evidence that coal dust played a role in the blast explosion.

The change will increase the amount of pulverized stone or other inert material that mines must use to dilute coal dust in tunnels that bring fresh air underground.

The change is based on federal research that shows decreasing the amount of coal dust in air intakes can help prevent explosions, Main said.

Mines must comply by Oct. 7 in new areas and by Nov. 22 in existing tunnels, Main said.

The coal industry expressed immediate support for the change, which is already a state requirement in West Virginia.

"West Virginia producers are complying,'' said Luke Popovich, a spokesman for the National Mining Association. "Many have carried it to their operations outside West Virginia.''

MSHA announced Friday that more than 1,400 of 1,803 samples collected inside the Upper Big Branch mine by investigators show excessive amounts of coal dust were present before the blast. The findings bolster MSHA's preliminary findings issued 10 days after the explosion that a mix of methane and coal dust caused the explosion.

The Associated Press reported Sept. 12 that handwritten logs recording inspections by Upper Big Branch employees showed eight conveyer belts had excessive amounts of coal dust 32 minutes before the explosion. Mine owner Massey Energy's chief counsel, Shane Harvey, has conceded that miners would have been unable to correct that violation before the blast. But Harvey insists that the mine was adequately dusted and the logs merely reflect reminders to dust the mine.

He repeated Massey's contention that dust samples collected months after the accident are baseless.

Harvey raised no immediate objection to the emergency rule.

"We'll analyze the regulation,'' Harvey said. "We agree that rock dusting is critically important in coal mines.''

Blankenship cited several examples of what he considers lies and misinformation from the agency. Among them were MSHA's decision to order two Massey employees out of the mine the day of the blast. MSHA has not publicly accused the pair of tampering with evidence as Blankenship claimed.

"It raises an issue about how much sense they have to think that someone would do that,'' Blankenship said.

He also blasted MSHA over claims that methane monitors at the mine had been tampered with to prevent them from working. Those accusations have come from current and former employees during congessional testimony.

Blankenship also repeated Massey's contention that methane entered the mine from a floor crack and overwhelmed safeguards such as ventilation equipment. MSHA has dismissed that notion.

Several of the victims apparently tried to cut off power to the mine's main mining machine in the seconds before the blast, Blankenship said.