CHARLESTON — The nation’s nearly 600 underground coal mines will be allowed to use conveyer-belt tunnels as ventilation shafts and be required to install airtight shelters for trapped workers under new federal regulations announced Tuesday.

The rules are the latest in a string of safety measures required by sweeping federal legislation adopted after three high-profile accidents, including the Sago Mine explosion, killed 19 miners in the first half of 2006. Final versions of the rules will be published Wednesday, the U.S. Mine Safety and Health Administration said.

“Both are significant and offer protections,” MSHA director Richard Stickler said.

The National Mining Association in a statement called the rules an improvement.

“Both rules recognize the importance of technological innovation for advancing mine safety as well as the difficulties presented by unproven and untested technologies in this environment,” spokesman Luke Popovich said in an e-mail. “We’re pleased that MSHA has accepted the use of belt air for ventilation and the advantages of our industry’s recent investments in new refuge chambers.”

Not everyone agrees with that assessment.

Allowing belt tunnels to double as ventilation shafts, for instance, has long been considered inherently dangerous, particularly by the United Mine Workers.

While a UMW spokesman had no immediate comment Tuesday, the labor union has maintained that pumping air through conveyer tunnels would push smoke directly toward miners in the event of a fire. Friction along conveyer belts and an often abundant accumulation of coal dust are a relatively common cause of mine fires.

Stickler, however, said requiring flame-resistant belts will improve safety by preventing disasters. Other parts of the rule require mines to replace heat sensors on belt lines with carbon monoxide detectors, better belt maintenance, reducing dust levels, and mandating smoke sensors for mines that ventilate through belt tunnels.

Those mines will require approval from MSHA district managers as well, Stickler said. “We think that in some mines, and based on the recommendations of the technical study panel — we had experts on there from industry and academia — and their recommendations, they recognized that there are situations where it’s safer to use belt air than to not use it.”

Mines will have one year to start using flame-resistant belts and 10 years to replace older belts that are already being used.

The requirement is expected to increase costs for underground operations that already face competition from lower-cost surface mines in Appalachia and the Powder River Basin in Wyoming and Montana, said Kentucky Coal Association President Bill Caylor. “The fire-resistant belts are obviously going to be more expensive and also, I would imagine, in the short term more difficult to obtain,” Caylor said.

The shelter rule likewise is raising concerns, particularly in West Virginia, which already requires airtight refuge chambers. Illinois also requires shelters in its underground mines.

Both West Virginia and MSHA require shelters with enough food, water and breathable air to keep trapped miners alive up to four days while they await rescue. But MSHA’s rule allows mines to build shelters in place and mandates larger shelters than the state, requiring 15 square feet of floor space per person.

“The shelters that have been approved by the states — West Virginia, Illinois and also by MSHA,” Stickler said, “While they don’t meet every technical specification of the new rule, they will provide protection for miners and we’re grandfathering those units for a period of 10 years or until they’re replaced.”

The MSHA rule effectively decreases the number of people that existing shelters can accommodate, said Randy Harris, an engineering adviser for the West Virginia Office of Miners’ Health, Safety and Training.

“That means you’re going to have to buy more of them,” Harris said. “The bottom line is, it’s going to cost the industry a lot more.”

West Virginia Coal Association Vice President Chris Hamilton estimated the state’s underground mines already have spent approximately $100 million on shelters. Hamilton praised MSHA for allowing West Virginia mines to use equipment they’ve already purchased.

“That’s good news,” he said. “We were concerned initially that the state may be penalized for displaying that leadership.”