U.S. President Donald Trump has postponed a phone call with Panamanian President Jose Raul Mulino due to last-minute changes in the U.S. leader's agenda, Panama's government said on Friday, amid tensions over U.

Panamanian President José Raúl Mulino on Thursday denied the U.S. State Department’s claim that his country had reached a deal allowing U.S. warships to transit the Panama Canal for free. Mulino said he had told U.

The State Department claimed it had struck a deal that would save the U.S. government “millions of dollars a year.”

The Panama Canal Authority on Wednesday denied the U.S. State Department's claim that U.S. government vessels would be able to cross the canal without paying fees, likely ratcheting up tensions after President Donald Trump threatened to take back control of the crossing.

Panama President Jose Raul Mulino on Thursday accused the United States government of lying a day earlier when the U.S. State Department claimed that U.S. government vessels would be able to cross the country's namesake canal without paying fees.

Secretary of State Marco Rubio on Thursday said it was "absurd" that U.S. government ships are charged to use the Panama Canal after Panama denied a claim that it had agreed to allow them free traversal.

The Panamanian leader says he was “incredibly surprised” by the statement, as President Trump threatens a U.S. takeover of the strategic waterway.

The Panama Canal Authority said in a statement late on Wednesday that it had not made any changes to charges or rights to cross the canal, after the U.S. State Department said that U.S. government vessels could transit the crossing without being subject to such fees.

Washington had suggested Panama had agreed to no longer charge fees for US government vessels using the waterway.