Authorities shut down part of Dulles International Airport near Washington on Saturday because of a suspicious object but later said no explosives were found.

Security concerns are running high in Washington and New York on the eve of the 10th anniversary of the Sep. 11 attacks on the Pentagon and the World Trade Center by al Qaeda militants using hijacked passenger planes.

The partial shutdown at Dulles came about 4:30 p.m. (20:30GMT) after an explosive-sniffing dog called attention to a freight item about to be loaded on a plane.

Four hours later, a spokesman for the Transportation Security Administration (TSA) said the cargo had been cleared.

Dulles spokesman Rob Yingling said the airport, about 22 miles (35 km) west of Washington, was operating normally after some planes were reassigned to other gates for arrival and departure.