ISLAMABAD, July 15 (Xinhua) -- A coalmine in Pakistan's southwest Balochistan province collapsed due to the accumulation of poisonous gas, trapping 11 miners thousands of feet deep underground, local media and officials said on Monday.

Shafqat Fayyaz, minister of Mines and Minerals Development of Balochistan, said that one mine worker was brought to safety during a rescue operation, while efforts are underway to recover the remaining 11 miners, who have been trapped for over 20 hours in the coal mine in Quetta, the provincial capital of the province.

The presence of poisonous gas inside the mine has been making the access to the miners difficult.

Local media reported that six relief workers participating in the rescue operation also fell unconscious due to toxic gas in the mine.

Chief Minister of Balochistan Jam Kamal Khan has directed the concerned authorities to deploy technical teams and ensure the safe recovery of the workers.

According to the Pakistan Central Mines Labor Federation, about 100 to 200 laborers die on average in coal mine accidents across the country every year.