Venezuelan officials are warning Colombia’s president that his meeting with Venezuela’s opposition leader could severely damage relations between the neighbouring countries.

Colombian President Juan Manuel Santos on Wednesday received Venezuelan opposition leader Henrique Capriles, who is trying to build international support for his efforts to overturn an April 14 presidential election he claims was fraudulent. Capriles narrowly lost to government candidate Nicolas Maduro.

Venezuelan Foreign Minister Elias Jaua told state TV that the meeting “will bring a derailment of the good relations that we have.” Parliament Speaker Diosdado Cabello compared the meeting to “placing a bomb on the train.”