AP quoted a federal official as saying that a handheld meter found deep inside the Upper Big Branch mine detected explosive levels of methane before a blast killed 29 miners the first concrete evidence of dangerous concentrations of gas ahead of the April 5 disaster.

Mr Kevin Stricklin official of Mine Safety and Health Administration said that the meter detected 5% methane in the Raleigh County mine's atmosphere.

The find could be significant because methane isn't explosive unless it makes up 5% to 15% of the atmosphere. While a preliminary report issued by MSHA in April blamed methane and coal dust for the explosion investigators continue to scour the underground mine to find where the blast started and what may have caused it.

Richmond Va based Massey Energy Company the mine's owner has said that high levels of methane may have poured into the mine and overwhelmed safeguards just before the explosion.

Previously, MSHA had said only that methane monitors from the mine hadn't been tampered with before the explosion. Former Massey employees claimed it was routine to electronically bridge machine mounted monitors to prevent them from cutting power if they detected methane approaching dangerous levels.

Mr Stricklin said that investigators found the handheld meter in an area near 6 bodies recovered near the mine's long wall mining machine. It was found several weeks ago and has been tested by the agency.

He said that investigators hoped to search the area again as soon as Thursday for more handheld gas meters. They should have found at least one more meter because miners routinely carry the devices among other things.

Meanwhile, Mr Stricklin said that we expected to find at least two remotes and we only got one. The one detector that we found was the one detector that had seen 5% of gas.

(Sourced from Associated Press)