Trump calls for free pass for US ships in key channels

US President Donald Trump says American military and commercial ships should be allowed to travel through the Panama Canal and Suez Canal free of charge.

"I've asked Secretary of State Marco Rubio to immediately take care of, and memorialise, this situation," Trump said in a post on Truth Social.

The Panama Canal crosses the narrowest part of the isthmus between North and South America, allowing ships to move more quickly between the Atlantic and Pacific oceans.

It carries about 40 per cent of US container traffic each year.

The US completed construction of the canal in the early 20th century but gave control of the strategically important waterway to Panama in 1999.

Trump has said repeatedly he wants to "take back" the canal. Before taking office in January, he told reporters he would not rule out using economic or military force to regain control over the canal.