The operator of a mine where an underground fire killed 292 workers admitted Friday that the complex did not have refuge chambers where crews could have taken shelter, but said the law didn’t require them.

“Legally, we don’t have an obligation to build” the shelters, Alp Gurkan, head of the Soma Group, told reporters. He said at a news conference that the company had been planning to install refuge chambers later this year.

The mine accident, Turkey’s deadliest industrial disaster, has prompted angry street protests in several Turkish cities and towns, and drawn harsh criticism of the government’s failure to effectively regulate safety. Prime Minister Recep Tayyip Erdogan, who had been widely expected to run for president later this year, has been a prime target of the public backlash.

The company promised a full investigation into the disaster, calling the fire “inexplicable.” Earlier, officials blamed an explosion in a power transformer for sparking the blaze, spreading deadly smoke and fumes through six miles of tunnels.

Despite the company’s insistence that it had taken proper safety precautions, there had long been warnings about conditions at the mine near the town of Soma. The Turkish Chamber of Architects and Engineers had said in a 2010 report that poor ventilation, absence of systems to track methane buildup, faulty wall supports and lack of emergency escapes put workers’ lives at risk, local media reported.

“No production should be made before the necessary research has been completed,” the report said, adding that safety deficiencies “might lead to disaster.”

Meanwhile, controversy flared over the number of miners still missing and presumed dead. Energy Minister Taner Yildiz said Friday the final death toll would likely be around 300, with 18 still missing. (Eight more bodies were found later Friday, bringing the number of dead to 292.)

A day earlier, the number of missing men had been put at more than 100.

The government said the confusion over how many miners were inside when the fire broke out was due to a shift change, but opposition parties allege that scores of illegal or underage workers were inside at the time. Britain’s Guardian newspaper quoted a miner who had been inside after the accident as saying that the tally of those still missing was much higher than the 18 being reported at the time.

“The miners who enter the mine use a card. The exact number of miners inside the mine should be clear,” main opposition Republican People’s Party head Kemal Kilicdaroglu told reporters after a visit to Soma this week.