A Brazilian air force helicopter emblazoned with the Red Cross logo has left an airfield in southeastern Colombia on a mission to pick up members of the last group of soldiers and police held by Colombia's main rebel group.

The departure on Monday was delayed for nearly two hours due to heavy rains.

The leftist Revolutionary Armed Forces of Colombia, known as the FARC, has promised to free the 10 captives, likely in several stages. All have been held for at least 12 years.

The rebels have proposed peace talks, and recently announced they had halted revenue kidnappings as a revenue source.