WASHINGTON (Reuters) - Secretary of State Marco Rubio said on Thursday he had "zero doubt" that China has a contingency plan to shut down the Panama Canal in the event of a conflict with the U.S. and that Washington intends to address what it sees as a national security threat.

Panama's President Jose Raul Mulino has ruled out negotiations with the US over ownership of the Panama Canal as he prepares to Marco Rubio.

PANAMA CITY (Reuters) -Panamanian President Jose Raul Mulino on Thursday ruled out discussing control over the Panama Canal in a meeting with U.S. Secretary of State Marco Rubio, who is set to visit the Central American country in his first official trip abroad this weekend.