A large rescue operation is under way to free hundreds of coal miners trapped underground after an explosion and fire in western Turkey left hundreds of their colleagues dead.

Early on Wednesday Turkey's energy minister, Taner Yildiz, said the death toll had risen above 200. Hundreds more were believed to be still trapped inside the mine, while more than 360 had been evacuated.

As rescue teams made their way from neighbouring regions, fresh air was being pumped into the mine in Soma, about 75 miles north-east of the Aegean coastal city of Izmir.

Twenty people initially made it out of the privately owned mine, where a power distribution unit was said to have exploded, but local authorities in the western province of Manisa said that between 200 and 300 workers were still underground.

The blast in the power unit of the mine triggered an electricity cut, making the lifts unusable and leaving hundreds of miners stranded underground.

The disaster management agency said authorities were making arrangements to set up a cold storage facility to hold the corpses of miners recovered from the site.

The accident happened about 2km inside the mine, according to Turkey's NTV television, while the rescue efforts were being hampered by the length of the tunnels.

Determining how many workers were trapped underground was made more difficult by the fact that the accident occurred during a shift change.

Yildiz said about 780 people had been working inside at the time of the accident.

Television footage showed people cheering and applauding as some trapped workers emerged out of the mine, helped by rescuers, their faces and hard hats covered in soot.

Medics, ambulances and relatives at the entrance of the mine. Photograph: AP

One wiped away tears on his jacket, another smiled, waved and gave a "thumbs up" sign to onlookers. Meanwhile, hundreds of relatives of miners who were working at the site gathered outside the mine and at the hospital in Soma, which is at the centre of a coal-mining community.

Yildiz said earlier that rescue efforts "must be completed by the morning".

"Time is working against us," he said, adding that about 400 rescuers were involved in the operation.

"We are faced with carbon dioxide and carbon monoxide poisoning."

Yildiz, who opened the mine 10 months ago, said some of the workers were 420 metres deep inside the mine.

"They are pumping oxygen into the mine but the fire is still burning. They say it is an electrical fault but it could be that coal is burning as well," Tamer Küçükgençay, chairman of the regional labour union, told Reuters.

Miners carry one of the rescued men after the explosion. Photograph: AP

The Turkish miner's union president, Vedat Ünal, said : "Every worker has a gas mask. Those masks provide oxygen. But we don't know how long they will last." The office of the Turkish prime minister, Recep Tayyip Erdogan, said that a planned one-day visit by him to Albania on Wednesday had been cancelled and that he would be going to Soma.

Erdogan said in televised comments: "Evacuation efforts are under way. I hope that we are able to rescue them."

Miners' representatives said that accidents such as the latest one would increase due to privatisations, the increasing employment of subcontractors and a lack of strong unions, all of which they said had led to massive pressure on workers to produce as much as possible for as little cost as possible.

"And because of weak unions it is impossible to counter this pressure," said Tayfun Görgün, the head of one of the mining unions.

Soma Komur Isletmeleri AS, which owns the mine, confirmed that a number of its workers were killed but did not say how many. It said the accident occurred despite "[the] highest safety measures and constant controls" and an investigation was being launched.

Turkey's main opposition Republican People's party sought to establish a parliamentary inquiry last year about safety issues in relation to the mining company, but the bid was rejected.

Mining accidents are common in Turkey, which is plagued by poor safety conditions. Turkey's worst mining disaster was a 1992 gas explosion that killed 263 workers near the Black Sea port of Zonguldak.

In May 2010 another gas explosion killed 30 miners, again in the same northern province.