One of the sources said US Commerce Secretary Wilbur Ross will also attend the meeting, which aims to discuss Venezuela's political crisis and build support for early elections.

Both sources asked not to be named because the list of attendees had not been announced.

A spokesman for Bolton declined to comment. The US Department of Commerce did not immediately respond to requests for comment.

Peru invited some 100 foreign ministers to the summit and had hoped to include Russia, Cuba, China and Bolivia. The idea was to foster dialogue between supporters of Venezuelan President Nicolas Maduro and his critics, Peru's foreign minister said when he announced the summit last month.

China and Bolivia have not confirmed whether they will attend, both sources said.

The head of the Inter-American Development Bank, Luis Moreno, and the European Union's representative on Venezuela, Enrique Iglesias, have confirmed their attendance, the sources added.