Thirty-two miners in eastern Ukraine were missing and feared dead on Wednesday following an explosion at a coal mine in the rebel-held city of Donetsk.
The blast took place at Zasyadko mine in the separatist hub of Donetsk, near the city's war-wrecked airport.
The chairman of Ukraine's parliament, Volodymyr Groysman, announced 32 miners killed in what he called a "terrible tragedy".
Mykola Volynko, head of the Miners' Union of Donbass, which covers the eastern region, confirmed that figure. "At the moment we know of 32 people dead. We don't know how many people are still in the mine," he told AFP.
But Grosyman later cast doubt on the fate of the miners, telling MPs that, "according to the latest information", 32 miners were unaccounted for, but that only one was confirmed killed.
Rescue workers were trying to locate a further approximately 45 miners, said the spokesman who did not wish to be named, adding the chances of finding them alive were "practically zero".
"At the moment there are still 70 people underground but the situation is constantly changing as we bring people to the surface," spokeswoman Julia Bedilo said, blaming the blast on trapped methane gas.
Donetsk has been the focus of a nearly year-long conflict between government forces and pro-Russian rebels.
Ukrainian Prime Minister Arseniy Yatsenyuk said he had ordered his energy and emergencies ministries to scramble rescue teams to the scene. But the rebels "did not allow Ukrainian rescue teams to reach the site and help save people's lives," he told a cabinet meeting.
"I demand that Ukrainian rescuers and policemen are granted access to the scene of the tragedy," he wrote on Twitter.
Anxious family members waited outside the mine for news of their loved ones.
Valentina Dzuba, 72, told AFP she had been waiting for seven hours for news of her son Vladimir, aged 47. "I heard the news on the TV," she said in tears. "We have no information. I fear he's dead."
Ukraine's coal mines are considered among the world's most dangerous, with many of them poorly financed and employing outdated Soviet-era equipment.
Most of the country's mine disasters are caused by build-ups of methane gas.
Zasyadko mine, which is one of the country's biggest, was the scene of the worst mining accident in the country's post-Soviet history in 2007, in which 101 people were killed.
The mine, which is owned by Yukhym Zvyahilsky, a member of the national parliament, lies on the outskirts of Donetsk, just a few kilometres from the frontline.
The facility has been caught in crossfire between the rebels and government forces on several occasions. On one occasion, miners were trapped inside after shelling knocked out its power supply.
The accident comes as the warring parties claim to be pulling back their artillery in line with the February truce.
Ukraine's army said on Wednesday it was pulling back 152-calibre howitzers, the "second stage" in the accord.
Meanwhile, near Mariupol, the biggest city in the conflict zone still controlled by Kiev, local security officials accused rebels of shelling Ukrainian positions in the village of Shyrokine. "The situation continues to be tense," a statement by the local security headquarters said.
One Ukrainian soldier was also reported dead in sporadic fire from the rebels, security spokesman Andriy Lysenko said.
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