U.S.-bound cargo at six overseas ports will be screened for nuclear and radiological material in an expanded effort to prevent terrorist bombs from entering American waters, federal officials said Thursday.

The Homeland Security Department said it would scan all containers bound for the United States in the ports of Qasim, Pakistan; Puerto Cortes, Honduras; and Southampton, England.

Radiological scanning will also be done at Port Salaleh in Oman, the Port of Singapore, and the Gamman Terminal at Port Busan in Korea, though not every container will be screened, officials said. Officials said the examinations would begin early next year at all six ports.

When fully operational, the program will screen about 8 percent of the 11 million cargo containers that reach U.S. shores each year.

The Southampton facility is operated by Dubai Ports World, the same company whose planned purchase of U.S. port operations caused an uproar in the U.S. Congress earlier this year. One of the chief opponents of that deal said the company had undergone closer scrutiny this time.

Homeland Security Secretary Michael Chertoff called the effort part of a strategy to "secure the global supply chain and cut off any possibility of exploitation by terrorists."

The program was created by Congress in September, but the agency said it was going beyond the legislation's requirement of screening in three foreign ports.

The Homeland Security and Energy departments will split the nearly $60 million (€45.1 million) cost of the detection equipment, ranging from large portals to handheld scanners.

The screening will be done by local port officials, but data from the sensors will be given instantly to U.S. Customs and Border Protection officers working in the overseas ports.

Sen. Charles Schumer, whose amendment to ports legislation created the program, said he wants the program to grow to more ports.

"It makes sense to focus this program on the ports that present the greatest risks, and we'll continue to fight to expand this program to ports around the world," Schumer said.

As for the agreement with Dubai Ports World, Schumer said "they have undergone significant scrutiny to join this program, unlike what we experienced in the first episode."