The United States studies the allegations made by the Colombian government according to which there are guerrilla leaders in Venezuela. Washington has been concerned "for a long time" about the possible presence of Colombian rebels in Venezuela, the US State Department spokesman Philip Crowley said.

The United States is studying the allegations made by Colombia according to which guerrilla leaders are hiding in Venezuela.

"We are studying these reports. Some of this is not new, since there has been concern for some time about cross-border activities or involvement in rebel activities," Crowley told reporters.

The Colombian government said on Thursday that it has evidence that leaders of the Revolutionary Armed Forces of Colombia (FARC) and the National Liberation Army (ELN) are hiding in Venezuela.

Venezuela is obliged to "prevent terrorist groups from operating in its territory," Crowley said.