For decades, Colombian citizens have been caught in the middle of turf battles between leftist guerrilla groups and right-wing paramilitaries.

In 2006 the largest of those right-wing groups - the United Self Defence Forces of Colombia - was officially demobilised and disbanded after striking a deal with the government.

But now there are concerns that remnants of these groups have joined forces, fuelled by a surge in drug trafficking, and are presenting a new threat.

Al Jazeera's Teresa Bo reports form the Choco region of Colombia.