Rescuers are battling to reach hundreds of workers feared trapped after an explosion at a mine in western Turkey that has killed at least 205 people in one of the nation’s worst industrial disasters.

As Turkey declared three days of national mourning, Energy Minister Taner Yildiz said the toll could rise to exceed the 263 workers killed in the country’s worst mining disaster.

“We are worried that human loss could increase,” he told reporters.

“The problem is more serious than we thought. It is developing into an accident with the highest worker death toll Turkey has seen so far.”

Yildiz said 205 miners had been confirmed dead after Tuesday’s blast at the mine at Soma, in Manisa province.

He declined to say how many people remained trapped in the mine, although earlier reports said 787 workers were underground when the blast occurred.

Turkey’s disaster management agency AFAD said 93 people had been rescued, 85 of them injured.

Explosions and cave-ins are common in Turkey, particularly in private mines where safety regulations are often flouted.

A miner is helped out by workmates. Photo: Getty

Turkey’s worst mining accident happened in 1992 when 263 workers were killed in a gas explosion in a mine in Zonguldak.

Tuesday’s explosion was believed to have been triggered by a faulty electrical transformer.

A security source said there were pockets in the mine, one of which was open so rescuers were able to reach the workers, but the second was blocked with workers trapped inside.

Hundreds of people gathered around the explosion site as rescuers brought out injured workers, who were coughing and struggling to breathe due to the dust.

Sena Isbiler, mother of one of the miners, stood on top of piles of wood, craning her neck to see who was being led out of the mine.

“I have been waiting for my son since early afternoon,” she said.

“I haven’t heard anything about him yet.”

Injured workers are carried from the mine. Photo: AAP

Arum Unzar, a colleague of the missing miners said he had lost a friend previously “but this is enormous.”

“All the victims are our friends,” he said as he wept.

“We are a family and today that family is devastated. We have had very little news and when it does come it’s very bad,” he added.

Fire officials were trying to pump clean air into the mine shaft for those who remained trapped some two kilometres below the surface and four kilometres from the entrance.

Injured people emerged from the collapsed mine, some walking, others being carried by rescue workers while being given oxygen, as security officers tried to keep ambulance routes clear.

Energy Minister Yildiz promised the government would “not turn a blind eye” to negligence.

“We will do whatever necessary, including all administrative and legal steps,” he said.

The mining company Soma Komur issued a statement saying it had taken maximum measures to ensure safety.

“The accident happened despite maximum safety measures and inspections, but we have been able to take prompt action.”

Turkey’s ministry of labour and social security said the mine was last inspected on March 17 and was found to comply with safety regulations.

A miner being helped by rescue workers. Photo: Getty

But Oktay Berrin, a miner, said workers were not protected underground.

“There is no security in this mine,” he said.

“The unions are just puppets and our management only cares about money.”

Prime Minister Recep Tayyip Erdogan was due to arrive in Soma on Wednesday after cancelling a trip to Albania.

Speaking in Ankara, the leader expressed his “heartfelt condolences” to the families of those who died.

“Some of the workers have been rescued and I hope we will be able to rescue the others,” Erdogan said.

Turkey’s President Abdullah Gul has cancelled a trip to China and will also travel to the scene of the disaster.

Yildiz told journalists in Soma that a team of 400 people were involved in the rescue effort and that the main cause of the deaths was carbon monoxide and dioxide poisoning.

He said fires and the risk of toxic carbon monoxide were hampering rescue efforts.

“I must say that our hopes about rescue efforts inside (the mine) are fading,” he added.

The miners are all thought to have gas masks, but it was not clear how long they would last.

FACTBOX

Recent fatal mine disasters

2014: Explosion and fire kill at least 200 workers at a coalmine in western Turkey; hundreds more remained trapped underground

2013: 83 workers buried by a massive landslide at goldmining site in mountainous area of Tibet, east of Lhasa, according to Chinese state media

2012: At least 60 people dead after a landslide at a goldmine in a remote corner of northeast Congo

2011: Fifty-two feared dead in southwestern Pakistan after a gas explosion deep in a coalmine in Sorange, near Quetta

2010: 29 men killed in New Zealand’s worst mining disaster in decades after a huge gas-fuelled explosion deep underground ends hopes of rescuing the South Island coalminers, who were caught in a similar blast five days earlier

2010: 33 miners rescued after being trapped for 69 days in a gold and copper mine in Chile’s northern Atacama desert

2010: 29 miners killed in an explosion at West Virginia’s Upper Big Branch coalmine

2007: At least 90 killed in post-Soviet Ukraine’s worst mining disaster, after a methane blast rips through tunnels deep below ground in a coalmine near the eastern city of Donetsk

2006: 65 coalminers killed in gas explosion in San Juan de Sabinas, in northern Mexico’s Coahuila state

AFP