Marco Rubio delivered a stark warning to Panama's president on February 2 that Washington would 'take measures necessary' if the Central American nation failed to curtail what the US describes as China's growing influence over the Panama Canal.

President José Mulino said Panama's sovereignty over the world's second busiest waterway is not up for discussion.

Secretary of State Marco Rubio is arguing that the presence of two Hong Kong companies and other Chinese firms violates a treaty Panama has with the United States.