YANGON, Sept. 11 (Xinhua) -- Rescue efforts for four miners trapped in a coal mine blast in Myanmar's central Magway region has been forced to be suspended as landslide in the coal mine hampered the rescue, the official Global New Light of Myanmar reported Tuesday.

The rescue efforts stalled after the rescuers entered about 180 meters into the coal mine and found scarcity of oxygen and a massive volume of harmful methane gas.

They also found a big rock which is too heavy to be moved.

Four miners were killed and five were rescued with four others missing in the coal mine blast in Saw town on Sept. 6, according to the initial report.

The incident took place at Tun Yarzar coal mine, operated by a private company, shortly after 13 miners entered into the mine and reached a depth of 90 meters.

Cause of the explosion was unclear.

In November last year, a previous coal mine collapsed in Minbu town due to explosion, killing eight miners.