Bogota (AFP) - Venezuela's joint military exercises with Russia should put the entire South American continent on alert against an "unfriendly act", Colombia's President Ivan Duque warned Wednesday.

Duque accused Venezuela of using the arrival of two Russian long-range bombers in Caracas as "provocative tools".

"The continent has to be alert," Duque told Colombia's RCN Television.

"This is not only an unfriendly act against Colombia, but an unfriendly act....against a region where there is something called the treaty of Reciprocal Assistance where, if there is any aggression, all countries should protect the country attacked," Duque said.

Two Russian long-range strategic bombers landed in Venezuela on Monday for what Caracas said were air force exercises aimed at strengthening the defence of the leftist-ruled South American country.

Bogota, which has emphatically denied socialist President Nicolas Maduro's claims that it is seeking his overthrow, said on Tuesday that it will continue to act with "prudence" during the wargames.

Colombia "does not allow itself to be intimidated, but neither does it allow itself to be provoked, nor does it go out to provoke our neighbors, any of our neighbors," said Defence Minister Guillermo Botero.

The two countries share a 2,200 kilometer (1,370-mile) border, but relations have been strained in recent years, with Duque and his predecessor Juan Manuel Santos branding Maduro a dictator.