The methane explosion last Friday which killed 13 miners could have been caused by either faulty gas sensors or safety equipment that had been tampered with.

Several days before the explosion, methane sensors detected higher concentration of the gas and miners were withdrawn from the area as a precaution.

However, on Friday the same sensors did not work properly, claims the Rzeczpospolita newspaper. Several minutes before the tragedy, the sensors showed a 1 to 2 per cent methane concentration, which was still within safety norms. But at 10.15 CET, the moment of explosion, the level of methane concentration suddenly jumped to 8 to 10 per cent.  

A special commission is investigating whether a high concentration of methane came before or after the explosion and where exactly in a 230-metres long corridor the gas accumulated. 

But one miner has claimed that the explosion was the result of a tampering with the sensors by management. The TVN 24 news channel showed a video on Saturday in which an anonymous miner said that methane sensors in the mine had been reset to boost coal output. The Public Prosecutor is looking at the claims. 

As a result of a methane explosion in the Wujek-Slask mine 13 miners died and 40 were injured. After the tragedy President Lech Kaczynski announced two days of national mourning starting on Monday. (mg)