At least 23 miners were killed and nine others injured in explosions at two coal mines in Pakistan's Balochistan province, an official said on Sunday.The first explosion, triggered by methane gas accumulation, on Saturday afternoon in Marwar, about 45 km from the provincial capital Quetta, killed 16 miners and injured seven others, the official told Efe news."A total of 24 workers were working in three branches linked to the main mine. The mines collapsed followed by a gas explosion and the exit points were dumped," the spokesperson said.Another explosion occurred a few hours later in a Spin Karez mine, about 60 km from Quetta, killing seven workers due to gas inhalation and injuring another two.The poor safety conditions in the Pakistani mines makes them prone to accidents.In 2012, 11 workers were buried in a mine in the northern part of the country while in 2011, some 50 miners died in Balochistan after a series of explosions triggered by gas leak in a coal mine.