At least 24 miners have been killed in a collapse in a coal mine in Afghanistan's northern Samangan province, officials said.



The collapse occurred after a gas explosion on Saturday evening at the Abkhorak coal mine, 300km northwest of the country's capital, Kabul.

They were working in a coal mine when part of the mine collapsed on them Mohammad Seddiq Azizi, Prcvincial governor's spokesperson



Emergency rescue teams rushed to the scene on Sunday, and successfully rescued all the trapped survivors.



Provincial governor's spokesperson Mohammad Seddiq Azizi said 24 bodies had been recovered and four that were still under the rubble had been pronounced dead.

He said 100 other workers were taken to hospital, but discharged after brief treatment.



Workplace safety standards are poor in Afghanistan as in many developing nations, and such accidents are common.



"Most of those injured are locals who rushed to the site to help those trapped in the mine," said Al Jazeera's Jane Ferguson, reporting from Kabul.



"These mines are often rudimentary, almost makeshift, in the way they are held up with wooden sticks - such incidents do happen here."



'Illegal mining'

Some mines employ children as young as 10 despite government regulations forbidding child labour, the government has said.



Javed Noorani of Integrity Watch Afghanistan, an Afghan non-governmental organisation, told Al Jazeera: "90 percent of mining in Afghanistan is illegal".



"In a hole that one or two people could barely fit in, they dig 30-40 metres deep," he said.

Afghanistan is estimated to be sitting on as much as $1tn in untapped mineral resources but decades of war and instability have kept most investors away.



The government says it expects to make as much as $4bn a year in mining revenues in the decade from 2014, when most Western forces are due to leave, compared with less than $150m from its resources sector last year.



The US Pentagon said in a 2010 briefing paper that Afghanistan's main resources were iron ore, with an estimated value of nearly $421bn, and copper deposits valued at $273bn.



But insecurity has hampered investment. Last year, work was halted at China Metallurgical Group's $3bn Aynak copper mine in the eastern province of Logar following attacks.