Foreign Minister Carlos Holmes said Colombia's intelligence services had been hearing chatter about alleged plans to kill the conservative Duque. He said the arrest in recent days of three Venezuelans in possession of assault weapons had heightened authorities' concern.
Blu Radio reported that the Venezuelans arrested in the northern Caribbean cities of Valledupar and Barranquilla this month had in their possession an assault rifle with a telescopic scope as well as a 9-mm mini-Uzi, ammunition and stun grenade.
Citing sources it didn't identify, Blu said any alleged plot would have likely had the support of armed Colombian leftist rebels or drug-trafficking organizations and would have been timed to coincide with the start of Venezuelan President Nicolas Maduro's second term next month.
Holmes' 90-second video did not cite any evidence and carefully avoided saying whether authorities had verified the existence of any conspiracy.
There was no immediate reaction from Venezuela's government.
Holmes appealed to Colombians to share any information that they have that could affect the president's safety. He also thanked the cooperation of unidentified foreign intelligence agencies for helping protect Duque.
Maduro in recent weeks has been ratcheting up his rhetoric against Colombia, accusing his neighbor of plotting with the U.S. to violently oust him from power.