US legislators are calling on the federal government to spend the billions collected from shipping companies to upgrade the country's ports and harbours.

About $10bn is sitting in the Harbor Maintenance Trust Fund, ready to be spent on US maritime infrastructure, Reps Peter DeFazio and Sam Graves wrote in a letter to President Joe Biden on Thursday.

"Without raising any taxes, the [Army Corps of Engineers] could spend significantly more funds to meet the growing maintenance dredging needs and ensure the continued competitiveness of our ports if we unlock the idle...