Colombia disputes Nicaragua's claim to certain areas in the Caribbean where it wants to promote oil exploration. REUTERS/Miraflores Palace/Handout

Colombia is warning Nicaragua against oil exploration in their disputed maritime border in the Caribbean area, Platts said Friday.

Juan Manuel Santos, Colombia's president, said through a diplomatic note sent by the foreign minister Maria Angela Holguin that Colombia would stop any offshore exploration Nicaragua might try to conduct. Nicaragua should not confuse "discretion" with inaction, Santos said in the note, which was delivered Thursday.

Colombia was responding to Nicaragua’s plan to offer 68,489 square kilometers of offshore Caribbean territory to energy companies, some of which isn't Nicaragua's to offer, says Colombian officials. “The Colombian government reiterates it will not accept nor permit exploration or the placement of exploration infrastructure to exploit hydrocarbons under concessions that presume to be offered by Nicaragua in areas that belong to Colombia," the letter read.

On July 17, Nicaragua announced that Noble Energy Inc. (NYSE:NBL), a Texas energy company, was going to spend $30 million to drill two offshore wells in Colombian waters of the Caribbean. In 2011 the government said the energy company had conducted seismic work in the area.

"We know where we stand and what we have to do," Santos said in Bogota. Santos also contends the disputed area in the Caribbean is in a Unesco-sanctioned biosphere called Seaflower, which contains a large coral reef and therefore should be protected against drilling.