As the final death toll from the Soma mine disaster in Turkey hit 301, police have made 24 arrests, including senior mining company executives. Further arrests are expected.

News of the arrests arrives as a preliminary report into the causes of the disaster, seen by Milliyet newspaper, highlights a shortage of carbon monoxide monitors in the mine and support beams made of wood rather than metal.

At a press conference on Friday, managers of the company responsible for the mine - Soma Holding - said the disaster was caused by an unexplained build-up of heat which made part of the mine collapse, causing a blaze to be fanned which spread rapidly through the tunnels. Mining executives deny negligence.

Speaking before his arrest, operations manager Akin Celik said: "We have all worked very hard. I have not seen such an incident in 20 years." Also detained by police was Soma Holding's general manager Ramazan Dogru.

Turkey's ruling AK Party says the mine was inspected 11 times in five years before the disaster and has promised a full-scale investigation into its cause. Economy minister Nihat Zeybekci said the government would do everything in its power to resolve the grievances of those affected. Energy Minister Taner Yildiz said anyone found guilty of negligence would be punished.

However, critics believe a government policy of selling off state-controlled mines to private companies seeking to maximise profits may have led to them skimping on safety.

The Confederation of Turkish Trade Unions organised a one-day strike in protest at the disaster, issuing a statement which read: "Hundreds of our worker brothers in Soma have been left to die from the very start by being forced to work in brutal production processes in order to achieve maximum profits. We call on the working class, labourers and friends of labourers to stand up for our brothers in Soma."

In the wake of violent protests across the country, in which teargas and water cannon were used on protesters, police in Soma set up checkpoints and arrested dozens of protesters. Prime Minister Recep Tayyip Erdogan received a hostile reception when he visited Soma last week, and appeared to slap a young man when he was bundled into a supermarket.

One of Erdogan's advisers, Yusuf Yerkel, was photographed kicking a protester held down by police. The protests in Ankara and Istanbul continue, with reports that a university with links to Soma Holdings has bene occupied by students. The university has announced plans to cut ties with the company.