Protesters turn over a vehicle belonging to the Kadikoy municipality during a demonstration blaming the ruling AK Party (AKP) government for the mining disaster in western Turkey, in Istanbul May 15, 2014. Rescuers were still trying to reach parts of the coal mine in Soma, 480 km (300 miles) southwest of Istanbul, more than 48 hours after fire knocked out power and shut down the ventilation shafts and elevators, trapping hundreds underground.

Soma, Turkey - Turkish police clashed with thousands of anti-government protesters angered by the deaths of at least 283 workers in the country's worst mining disaster, piling pressure on Prime Minister Recep Tayyip Erdogan.

In the western city of Izmir, about 100 kilometres (60 miles) from Soma, which was hit hard by Tuesday's mine explosion, police fired tear gas and water cannon at around 20,000 protesters on Thursday.

Turkey's four biggest unions held a one-day strike, saying workers' lives were being jeopardised to cut costs, and demanding those responsible for the collapse of the coal mine be brought to account.

“Hundreds of our workers have been left to die from the very beginning by being forced to work in cruel production processes to achieve maximum profits,” they said in a joint statement, calling on people to wear black.

Anger at the disaster has swept across Turkey, where mine explosions and cave-ins are a frequent occurrence.

In Izmir, the 61-year-old head of one of the main unions Kani Beko was hospitalised after violent clashes with riot police.

In Ankara, police fired tear gas and water cannon on around 200

protesters accusing the government and mining industry of negligence.

Erdogan has rejected claims of government culpability, saying that “such accidents happen”.

He compared the collapse to 19th-century mining disasters, saying that “204 people died in the UK in 1862 and 361 people in 1864”, in an apparent attempt to downplay its severity.

Erdogan was forced to take refuge in a shop after a furious reaction from relatives of the victims and the missing, some of whom began kicking his vehicle.

Photographs of his advisor Yusuf Erkel kicking a protester in Soma sparked outrage on social media.

Defending his actions, Erkel told Hurriyet newspaper: “He attacked and insulted me as well as the prime minister. Should I have stayed silent?”

At a protest in central Istanbul on Thursday near the city's emblematic Taksim square, the site of weeks of violent anti-government protests last year, angry demonstrators held the country's leaders responsible for the disaster.

“We're not being told the truth about the number of those who died or are trapped,” 20-year-old Sinan Cikar lamented. “If necessary precautions had been taken such an accident would never have happened.”

Another young protester took issue with Erdogan's mention of 19th-century mining disasters. “But we live in 2014,” he said.

“This is not fate but murder,” shouted another, Ezgi Kurt, 24.

President Abdullah Gul, on a visit to the mine, vowed action to prevent further such accidents.

“Whatever necessary will be done. We need to review all the regulations, like all developed countries do, so that these accidents do not happen again,” he said.

UN chief Ban Ki-moon expressed his condolences saying he was “deeply saddened by the coal mine tragedy” and expressing confidence that “the causes will be investigated expeditiously and that measures will be taken to prevent such disasters in the future”.

It is unclear how many workers were still trapped underground following the blast believed to have been set off by an electrical fault.

Mining operators put the figure at 90, but reports from rescue workers suggest the figure could be much higher. Most miners died of carbon monoxide poisoning.

Kemal Ozkan, assistant general secretary of the international trade union federation IndustriALL Global Union, said the “staggering” number of fatalities made the mining disaster the worst in recent memory.

“Turkey has possibly the worst safety record in terms of mining accidents and explosions in Europe and the third worst in the world,” he told AFP in a statement.

He added it was “made all the more tragic by the seemingly uncaring attitude of the government and mining companies”.

The disaster has added to the huge political pressure on Erdogan, two weeks before the first anniversary of the start of mass anti-government protests in Istanbul and after a corruption scandal involving his family and key allies in recent months.

“If the claims of negligence at the mine prove true, it will have a political price,” Professor Ilter Turan of Istanbul's Bilgi University told AFP.

Intensifying the pressure on Erdogan, local media reported that the general manager of the mine operator Soma Komur, Ramazan Dogru, was married to a member of his ruling Justice and Development Party (AKP).

Sinan Ulgen, head of the Istanbul Centre for Economics and Foreign Policy Studies, warned the government would struggle to contain the fallout from the disaster.

“Is this an act of God, or a case of negligence? We don't know. The government must demonstrate the political will to comply with EU standards on work health and work safety in order for this catastrophe not to become a political minefield,” he told AFP.

Early reports said 787 workers were underground when the blast occurred. By late Wednesday, “close to 450” workers had been rescued, according to Soma Komur.

But accounts from rescue workers cast doubt over these numbers.

Erdem Bakin, a doctor with the Search and Rescue organisation, said only around 70 to 80 people who were between the mine entrance and the transformer that exploded had survived.

The prosecutor's office in Soma, a key centre for mining lignite, a type of coal, has launched an investigation into the disaster.

The main opposition Republican People's Party (CHP) said it asked parliament last month to investigate work-related accidents at coal mines in Soma, but the government turned down the request.

“We receive tip-offs every day that workers' lives are under threat,” local CHP lawmaker Ozgur Ozel told Turkish media.

Turkey's ministry of labour and social security said the Soma mine had been inspected eight times in the last four years, most recently on March 17, and was found to comply with safety regulations. - Sapa-AFP