Twelve miners were killed and about 10 injured Saturday after two gas explosions at a mine in southwestern Romania, in one of the worst such accidents in recent years, officials said.
  
Eight miners were found dead while eight others were injured after a first blast at the Petrila mine in the afternoon, Interior Minister Cristian David said.
  
But a second explosion occurred about four hours later, killing three rescuers who had gone down to bring out the bodies, David said. A fourth later succumbed to his injuries, bringing the death toll to 12.
  
Rescue teams were ordered to return to the surface immediately after the second blast, in which up to three others were injured.
  
Those injured were meanwhile brought to hospital, local emergency services spokeswoman Anemona Doda said. Six of them had suffered serious burn injuries and had undergone surgery, according to the hospital.
  
"The explosion occurred at a depth of 950 metres (3,116 feet), due to a concentration of methane gas," the director of the national coal company CNH, Daniel Surulescu, said, referring to the first explosion.
  
Several ambulances were rushed to the scene while rescue teams descended into the mine, one of the deepest in Romania, to check if miners may still be trapped inside.
  
Anxious relatives of the victims gathered outside and complained about the lack of information about casualties, the Mediafax agency reported.
  
One miner who asked not to be named told Mediafax that methane gas levels in the mine already exceeded accepted limits on Monday but that he and his colleagues had nevertheless continued their work.
  
An inquiry has been launched to determine whether the mine's bosses were guilty of negligence.
  
Prime Minister Calin Tariceanu has also asked the economy, labour and interior ministers to travel to the mine "to help with rescue efforts," according to a government statement.
  
Working conditions at the Petrila site, one of the oldest in the country, are especially difficult, prompting unions to regularly demand further investments to improve safety.
  
"The authorities must understand that it is no longer possible to work with a shovel, we have to modernise the equipment," said union representative Zoltan Lakatos.
  
Since 1990, several explosions have occurred in this mining region, the most serious in August 2001 in Vulcan, when 14 people were killed.
  
In January 2006, seven miners were killed and five injured in an explosion at another mine nearby in Anina.
  
The Jiu valley is Romania's main mining region but has seen the number of miners drop to 11,000 from 46,000 in 1990, following the closure of several unproductive sites under a plan financed by the World Bank.
  
According to a government energy strategy, Romania will decide in the next few years whether to invest in maintaining the unprofitable mining sector or turn to new sources of energy.