Injured miners were rushed to a hospital in Cucuta after the blast [Reuters]

Twenty-one coal miners have been killed and six others injured in a explosion in northeastern Colombia, officials have said.

Wednesday's blast occurred in the La Preciosa mine in the Sardinata municipality in Norte de Santander department.

The mining regulator Ingeominas said the explosion was probably caused by a build-up of methane gas.

"They've just told me there are 20 dead and six wounded," Marisa Fernandez of Ingeominas told Reuters news agency.

Colombia's Red Cross said that eight bodies had been recovered so far along with six injured.

William Villamizar, the provincial governor, told RCN radio that a methane blast "exploded like a cannon shot, creating a flame inside the mine."

Civil defence, firefighters and military personnel were at the scene helping in rescue efforts.

Villamizar said the mine is under the "rigorous control" of national safety inspectors.

Previous accidents

However, six miners were killed and two others injured in a similar accident in the same mine in October 2010.

Alvaro Silva, a senior Sardinata municipal official, said about 30 people were also killed in another accident at the mine in 2007, even though the site, which produces coal for the local market, met
safety standards.

Nearly 100 coal miners were killed in work-related accidents across Colombia in 2010, according to government figures.

In June, a blast killed around 70 minersin another Colombian mine.

Julio Fierro Morales, a geologist and mining industry expert, said the Colombian government lacks resources to properly monitor mine safety.

"It is possible to diminish the frequency and probability of these accidents in Colombia with gas detectors and measures to prevent mine shaft collapses," Fierro Morales said.

He said mine owners were clearly not meeting safety standards, and the government did not have the resources to enforce the rules: 50 inspectors oversee 10,000 mines, 4,000 of which are currently being operated.

Source: Agencies