Colombia claims that two Venezuelan military aircraft violated sovereign airspace on Saturday and said on Monday that it would launch a formal protest.

The Colombian defense ministry said the planes overflew the Alta Guajira zone for nearly two miles and approached an army unit located in the area near the northern border with Venezuela. The ministry did not describe the type of aircraft detected.

"The air defense system of the Colombian Air Force was able to detect the entry into Colombian territory of two Venezuelan military airplanes," the statement detailed. "Initially, [they] entered 2.9 kilometers into Colombian airspace ... and later, the two Venezuelan military aircraft overflew a an National Army military unit in the La Flor region."

Caracas, for its part, denied on Sunday that Venezuelan aircraft had illegally entered Colombian airspace, Telesur noted. Foreign Minister Delcy Rodríguez said there was "no evidence" of such flights, the semi-official television network added, and Bogotá was trying to "frustrate" a planned meeting between President Nicolás Maduro and his Colombian counterpart, Juan Manuel Santos.

Santos said on Sunday that he had ordered his foreign and defense ministries "to launch a formal protest tomorrow against Venezuela for violating our airspace."

Both Maduro and Santos have repeatedly reiterated their willingness to discuss the border crisis that has led to a grave deterioration in the ties between their nations, but delegations from Venezuela and Colombia have not been able to agree on the details of such an encounter.

Citing "satisfactory advances" in dealing with the "sensitive issues," Rodríguez and Colombian Foreign Minister María Ángela Holguín on Saturday did, however, agree to renew diplomatic contacts that had previously been interrupted, Agence France-Presse reported.

An Aug. 26 meeting between Rodríguez and Holguín did not yield any advances in the border crisis, which has led to the expulsion of thousands of undocumented Colombian immigrants, as well as the shutdown of normally busy checkpoints between the two countries.

The governments of Ecuador and Uruguay, meanwhile, have been urging officials in Bogotá and Caracas to normalize their ties, and organized Saturday's meeting in Quito, the newswire said.