One of Colombia's most-grizzled and important rebel fighters is calling on President Barack Obama to do more to support peace and to free a guerrilla leader jailed for more than a decade in the United States.

Speaking in his jungle hideout in southern Colombia, the guerrilla commander known by the alias Martin Corena said such a move would be the best way for the Obama administration to back with actions its public support for an approaching deal to end decades of fighting.

"There's been a lot of statements and verbal demonstrations of support, but in practice, up to now, the support of the United States hasn't been viable and hasn't become real," Corena said.

The Revolutionary Armed Forces of Colombia considers Ricardo Palmera to be a prisoner of war.