ISTANBUL/ANKARA, May 14 -- Turkish Prime Minister Recep Tayyip Erdogan said Wednesday that the death toll from Turkey's coal mine accident Tuesday has risen to 238.

In statements at the site of the accident in the western province of Manisa where 120 others are still trapped underground, Erdogan vowed that rescue efforts would continue unabated and the government would investigate the accident thoroughly.

Erdogan's pledge comes amid anti-government protests in Istanbul, Ankara, Izmir, Antalya and other cities over the latest mining accident. The protesters were demanding the resignation of the ruling Justice and Development Party, AKP.

More than 500 people gathered in front of the Soma Holding headquarters in Istanbul around noon Wednesday.

In the capital Ankara, riot police fired tear gas and water cannon at hundreds of university student protesters who tried to march to the Ministry of Energy, daily Hurriyet reported.

The Worker Unions announced a nation-wide general strike on Thursday.

"No negligence in rescue operations will be tolerated and no one will be permitted to exploit the situation," Erdogan said.

He urged people to only trust the government figures rather than those released by "opportunists."

He emphasized that the Soma mine was seen as one of the safest in Turkey despite the accident.

Erdogan and other government officials arrived in the site of the accident, about 480 km southwest of Istanbul, on Wednesday, one day after what could be the worst coal mine disaster in Turkey 's history.

"Unfortunately these kind of mining accidents inevitably take place everywhere in the world," he said. "However, the enormity of this accident has hurt us deeply," said Erdogan.

During a press conference, Erdogan defended his government over its mining safety record, referring to a mine accident in Britain in 1838.

"I went back in British history. Some 204 people died there after a mine collapse in 1838. In 1866, 361 miners died in Britain. In an explosion in 1894, 290 people died there," Erdogan said in Soma.

"Take America with all of its technology and everything ... In 1907, 361 (miners died there)," Erdogan said. "These are usual things."

Nevertheless, he thanked the opposition parties and the media for their non-partisan response to the national tragedy.

Mining accidents kill dozens of miners each year in Turkey.

The last major mining tragedy in Turkey occurred in 1992, when a fire and explosion killed 263 people. Two other big mining accidents took place in 1983 and 1990, leaving 103 and 68 dead respectively.

Turkish President Abdullah Gul has cancelled an official visit to China, scheduled for May 15-21, over the disaster. Erdogan has also called off a trip to Albania.

Also on Wednesday, a coal mine operating without a license collapsed in Gelik village of the Black Sea province of Zonguldak in northern Turkey, trapping the owner underground, according to private Dogan News Agency.