Experts on operations at the port of Baltimore, a major shipping center on the U.S. east coast, reported to Congress Friday on efforts to boost anti-terrorism security while maintaining expected levels of efficiency.

In a presentation on Capitol Hill, University of Maryland transport specialists said the port of Baltimore has greatly improved security. The efforts are being coordinated by the new U.S. Department of Homeland Security and involve both state and local government agencies.

The focus was on cargo containers, the large metal boxes that are now the staple of the transportation industry worldwide. Forty-five million cargo containers enter U.S. ports daily. Their loading and transportation are done by foreign entities, whose cooperation on matters of security is considered vital. Once the containers arrive in the United States, said one expert, it may be too late to avert a disaster. John Porcari, the former transportation chief for the state of Maryland, says it is impossible to check the contents of each container.

"Every day you have containers arriving that are owned by one company, coming, say, to the port of Baltimore on a ship owned by a second company," he said. "The contents were put in there by a third company. They are lifted onto a chassis owned by a fourth company. And they are on their way to a company owned by another entity."

Containers are randomly inspected in the port of Baltimore and high technology products to enhance security are being installed. Tracking documents are increasingly transmitted electronically and arrive at the incoming port well ahead of the actual container.

Mr. Porcari, now a vice-president at the University of Maryland, says it is impossible to overstate the risk of a terrorist attack at the ports. The job is, he says, to balance the need for security with smooth, efficient operation. So far, he says, significant progress has been made without a noticeable decline in efficiency.