Efforts were under way on Tuesday night to rescue up to 300 miners who were trapped underground following an explosion and fire in Turkey which is also feared to have killed at least 17 of their colleagues.

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

Twenty people were initially rescued from the mine, where a power distribution unit was said to have exploded, leaving between 200 and 300 workers underground.

The accident occurred just over a mile deep in the mine, according to Turkey's NTV television, which reported that ambulances were seen entering and leaving the area.

"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 Kucukgencay, chairman of the regional labour union, told Reuters by telephone.

The head of the Turkish Mineworkers' Union, Nurettin Akcul, said that five workers had been killed in the blast.

Turkey's energy minister, Taner Yildiz, said a number of miners had died but refused to give an exact number, telling reporters: "It is a serious accident."

"Our priority is to reach our miner brothers … any figure we give could well be wrong."

Mining accidents are common in Turkey, which is plagued by poor safety conditions. The country's worst mining disaster was a 1992 gas explosion that killed 270 workers near the Black Sea port of Zonguldak.

An administrator in Soma, Mehmet Bahattin Atci, told reporters that 20 people were rescued from the mine but one later died in the hospital.

Television footage showed dozens of fellow workers and family members gathering outside the hospital in Soma, a coal-mining community in Turkey's western province of Manisa.

It emerged on Tuesday evening that the main opposition Republican People's party (CHP) made a parliamentary inquiry last year about the safety of the mining company that was rejected on 29 April.

Before leaving for Manisa, Yildiz said: "The rescue teams at work [in Soma] are very experienced. The main issue is to get clean air to the miners [trapped underground]."

Speaking at an award ceremony Turkish prime minister Recep Tayyip Erdogan extended his condolences to the families of the miners who died and underlined that rescue teams were doing everything to free the trapped workers.