WARSAW (REUTERS) - Rescuers were battling on Saturday (May 5) to reach five coal miners who were trapped nearly one kilometre underground in southern Poland after an earthquake.

The 3.4 magnitude quake hit the Borynia-Zofiowka-Jastrzebie mine on Saturday morning, trapping seven miners at a depth of about 900m, state mining office WUG said.

Two had been reached by mid-afternoon and rescuers were thought to be within 150m of the remaining five, the Chief Executive of mine owner JSW, Daniel Ozon, told a news conference.

The two rescued miners were in a "relatively good condition"and could walk unaided, he said.

There were about 250 people working in the mine at the time of the quake, JSW said. The missing miners were from a team of 11 that were drilling a new tunnel. Four had managed to escape by themselves.

The rescue operation was earlier hampered by high levels of methane, which reached a concentration of up to 58 per cent.

A spokeswoman for JSW, the European Union's largest coking coal producer, said earlier it would only be possible to check if installations supplying oxygen to the mine had not been damaged in the area of the quake once rescuers got there.

Katarzyna Jablonska-Bajer added that the quake had destroyed communications lines.

Prime Minister Mateusz Morawiecki, who was due to reach the mine later on Saturday, described the rescue operation as very difficult.

"I still hope that the remaining five miners will be saved," he told reporters.

WUG said the quake was of a type that can occur in coal mines after the removal of deposits builds up tensions in the rocks.

Polish news agency PAP said family members of the missing miners had gathered at the mine and were being counselled by psychologists.