Panamanian President José Raúl Mulino has denied claims by US president-elect Donald Trump that there are Chinese soldiers stationed at the Panama Canal.

In recent days Trump has threatened to take the canal back into US control, accusing Panama of "ripping off" the US by charging high shipping rates.

In a message posted to his Truth Social account on Wednesday, Trump wrote: "Merry Christmas to all, including to the wonderful soldiers of China, who are lovingly, but illegally, operating the Panama Canal".

Mulino called the claim "nonsense" and said that there is "absolutely no Chinese interference".

"There is not a single Chinese soldier in the canal," he told reporters in Panama City.

Mulino also rejected the possibility of reducing tolls for US ships or ceding control of the canal, a major shipping channel which connects the Atlantic and Pacific oceans.

"The canal is Panamanian and belongs to Panamanians. There's no possibility of opening any kind of conversation around this reality," he said.

After breaking ties with Taiwan, Panama established diplomatic ties with China in 2017, and Mulino said relations between the two countries were "respectful, well-managed … in terms of what is in the interest of both countries."

His comments came a day after Trump said he would nominate a Florida lawmaker to be his ambassador to Panama.

Kevin Marino Cabrera, a Republican commissioner in Miami-Dade County, worked for Trump's 2020 campaign and this year was Florida's representative to the Republican National Committee.

Announcing his pick in a Christmas Day post on his Truth Social network, Trump said Cabrera "will do a fantastic job representing our Nation's interests in Panama!".

The president-elect also repeated claims that Panama is "ripping us off".

On Sunday, Trump told a crowd of conservative activists: "The fees being charged by Panama are ridiculous, highly unfair."

If shipping rates are not lowered, Trump said, "we will demand that the Panama Canal be returned to us, in full, quickly and without question".

Trump has also said he did not want the Panama Canal "falling into the wrong hands" and specifically cited China.

China is the second-largest user of the Panama Canal after the US, according to data, and also has major investments in the central American country.

On Christmas Day, Trump fired off dozens of messages defending his policies and nominations, and repeated suggestions that the US annex Greenland and Canada.

It is unclear how serious Trump is about the territorial moves, or how they would be accomplished.

Up to 14,000 ships travel through the 51-mile (82km) canal each year, including container ships carrying cars, natural gas and other goods, and military vessels.

The canal was built in the early 1900s. The US maintained control over the canal zone until 1977, when treaties gradually ceded the land back to Panama. After a period of joint control, Panama took sole control in 1999.

Canal transit costs have increased over the past year due to a historic drought, according to shipping industry website Lloyd's List.

A Hong Kong-based company, CK Hutchison Holdings, manages two ports at the canal's entrances.