TEHRAN -- Police in Seattle, United States have found traces of TNT and military-grade explosives in truck rented by two Israelis that was pulled in the country's northwest last week, a report said Monday.

Fox News said the rented truck was pulled over Tuesday by police in Oak Harbor, a town which lies near a U.S. naval base in the state of Washington.

The report came amid a lingering terror alert in the United States following September 11 suicide attacks that killed some 3,000 people.

The station quoted documents read to it by unidentified sources as saying that traces of TNT were found on the gear lever while indications of RDX plastic explosives were found on the steering wheel.

The rented truck's passenger and driver, both Israeli nationals, were detained for alleged immigration violations after it was revealed they were allegedly in the United States illegally, Fox said.

Authorities in Washington state could not immediately confirm the report, AFP reported.

Fox said police stopped the vehicle early Tuesday after it was allegedly spotted speeding near the Whidbey Island naval air station.

The driver and passenger told officers they were delivering furniture, but a bomb-sniffing dog detected traces of explosives while tests later confirmed the presence of TNT and RDX, a military-quality explosive.

Fox quoted officials as saying an investigation was ongoing and no other charges have been filed against the driver and passenger.