Guinean police released 12 activists on Sunday after detaining them overnight for calling street protests as a general strike tightened its grip on the West African country and threatened its key mining sector, according to Reuters. Police arrested the group for inciting violence during a raid on the headquarters of the National Council of Civil Society Organisations (CNOSCG), an umbrella group which had called on Guineans to stage protest marches from Monday to increase pressure on President Lansana Conte's government. Unions leading an indefinite strike -- the third nationwide labour protest in a year -- have called on Conte to step down, saying his ailing health meant he was no longer fit to rule. "All our members who had been arrested yesterday have been freed. There were 12 of them, and they were held at the Central Prison in Conakry," CNOSCG President Ben Sekou Sylla told Reuters.