Agency spokesperson Amy Louviere told ILN that in order to do the water pressure and functionality testing, its investigators needed water. However, Massey will not supply the water and has said the tests could tamper with or taint evidence for its internal investigation.

“MSHA is attempting to negotiate with Massey to come up with a reasonable solution,” she said.

“We would like to avoid taking legal action. However, if we can’t reach a resolution, we will consider using any tools at our disposal that we feel are warranted.”

The agency also told media Tuesday that at least four spray devices were missing from the longwall shearer.

Massey vice-president and general counsel Shane Harvey told ILN that the company did not have an issue with testing the shearer but felt that a complete evaluation of the area around the shearer was “imperative” before inundating it with water.

“This area includes a floor crack that may have allowed natural gas to inundate the mine,” he said.

Harvey also noted that federal investigators had attempted to force the producer to destroy critical evidence as well as keep it from applying the latest technology in its own investigation of the blast that killed 29 workers.

“The company has sought MSHA's cooperation, but MSHA appears reluctant to allow any investigation that may reach a conclusion different than the one MSHA reached mere days after the explosion on April 5,” he said.

“The families deserve a thorough investigation using the best technology and the company is doing its best to provide this."