A South Carolina State Ports Authority proposal to charge a security fee of $1 per foot of a ship's length has drawn opposition from steamship lines who say the cost should be shared by truckers and others, The Associated Press reported.

The surcharge, which would be the first in the nation, could take effect in July. It's expected to generate $1 million a year to cover increased port security costs.

Shipping lines, in a letter to the authority, say the fee should be spread out so cargo owners, truckers, rail carriers, stevedores and others pay as well.

"Under the circumstances, imposing a new security surcharge on steamship lines, which represent just one segment of your user population and which have already borne the costs of their own security implementation, is unwarranted," the letter said.

"We strongly oppose the implementation of a security surcharge," added the letter addressed to Harry Butler Jr., chairman of the State Ports Authority board.

The letter was signed by representatives of 21 shipping companies representing about 80 percent of the cargo volume that moves through Charleston each year.

Meanwhile, the authority is pursuing a pact known as a "Maritime Security Discussion Agreement," in which other ports, terminal operators and shipping lines nationwide would agree on a uniform package of security fees.