Meeting all inspections is part of the agency's aggressive 100 Percent Plan, launched in October last year after the agency admitted "challenges" in completing regular health and safety checks at US coal mines – a shortfall that had come under attack by several industry groups.

The Mine Act requires MSHA to inspect every underground mine four times a year and every surface mine twice a year.

MSHA made the quarterly and twice-yearly inspections at more than 14,800 active mining operations around the country during the year.

Agency acting assistant secretary Richard Stickler attributed the success to several factors, including the willingness and work ethic of MSHA employees, the temporary reassignment of MSHA inspectors to areas where they were most needed, the provision for increased overtime for additional hours needed to complete inspections, and better oversight and tracking of inspections by the agency's district offices and headquarters.

Nearly 190,000 hours of inspector overtime were logged during the 2008 financial year. More than 172,000 citations and orders were written in that same time period.

Since July 2006, MSHA has hired more than 360 new coal enforcement personnel, and the 2008 fiscal year budget allocated funding for the hiring of 55 additional metal/nonmetal enforcement personnel.

However, MSHA said it can take up to 18 months for a new hire to become fully trained as a mine inspector. Once these new enforcement personnel receive their certifications, MSHA's enforcement ranks will be at their highest level since 1994.