Cauca province is a rebel stronghold and the army says its presence there is key.

BBC: Indigenous Colombians free soldiers held for 24 hours

Colombia now has five distilleries amid the sugarcane fields of the Cauca Valley, which produce 360m litres a year.

ECONOMIST: America and its neighbours discover a common interest

Cauca y Valle del Cauca, en el suroeste y Arauca en el noreste.

BBC: Mundo | Am��rica Latina | Colombia: rev��s para Uribe

The contractors, working for Canada's Gran Tierra Energy, were taken hostage in the southern Cauca region, Reuters news agency reports.

BBC: Soldiers and Farc rebels killed in clashes ahead of talks

The police officers were taken in Valle del Cauca, another department in southwest Colombia, and had been held since January 25.

CNN: Colombian rebels release soldier