Police in northeastern Turkey have clashed with hundreds of activists and local residents trying to prevent the construction of a copper mine in the region.

Residents fear that the mine will ruin the environment and damage forests in the mountainous Cerattepe area, in the Black Sea coastal province of Artvin, which borders Georgia. The protesters have used dozens of vehicles and barricades on a road in Cerattepe to block the construction vehicles' access to the mine site.

Police on Wednesday began towing the vehicles away and, for a second day running, used tear gas to disperse the group. Some protesters were seen hurling rocks at police.

The private Dogan news agency says at least four activists have been detained.