Forensic anthropologists digging around the World Trade Center site for overlooked victims' remains have found what appears to be debris from the towers under a service road and plan to widen the search, officials said Friday.

The discovery comes amid a renewed hunt for remains of victims of the Sept. 11, 2001 terror attack that began in October after utility crews came upon some bones in an abandoned manhole, which had been paved over and forgotten along the western edge of the trade center site.

With all the new paving and work that was done in the rush to finish the trade center cleanup during the spring of 2002, that manhole and a number of other subterranean pockets were never searched for victims' remains.

Officials have also been eyeing the loose landfill that surrounded the manholes as another potential hiding place for lost human remains. The city recently began digging a five-foot-(!.5-meter) wide trench through that area, which is known as the haul road, to test whether the entire pathway should be unearthed and all the fill should be sifted.

In a memo updating Mayor Michael Bloomberg on the remains operation Friday, Deputy Mayor Ed Skyler said that debris has turned up in the loose material, and that the city will expand the digging there.

"Based on the appearance of what could be WTC-related debris in the trench, the majority of the haul road requires further excavation," Skyler wrote.

Crews sifting the material have found a variety of items like computer parts, office carpeting, electrical wires and steel from the building. No human remains have been found in the loose fill; the only remains that have turned up since the renewed search began in October were some 200 bones in the initial manhole, plus a handful of fragments in three other manholes.

As to how hundreds of bones ended up in manholes, one theory is that loads of debris leaked in after large sharp pieces of steel pierced the ground and poked holes into the underground utility cavities.

No remains have been identified for about 40 percent of the 2,749 people killed in the Sept. 11 attack. None of the new discoveries have been matched to any of the dead, but the medical examiner is working to do so.

Many families of the victims have pushed for a wider excavation under the service road because they are concerned that the loose fill contains human remains. Some believe that crews in 2002 used rubble from the towers instead of clean soil when they were excavating the disaster site and building the road.

"Thank God. Thank God they're finally doing this," said Tim Sumner, whose brother-in-law, firefighter Joseph G. Leavey, was killed in the terrorist attacks.

Officials maintain that no debris was used as fill and that the trade center materials being found under the road now are coming from a very bottom layer that was likely compacted under the mountain of rubble, and then eventually covered over with the clean soil.

Officials who have worked in the initial recovery operation at ground zero have told The Associated Press that they believe steel and other items were buried over 10 feet below the service road and could be attached to debris or remains. They have also told the AP that they believe many things were overlooked because the city was rushing to finish the cleanup job.

Skyler also told the mayor on Friday that officials had identified an additional 165 underground areas, including manholes and subterranean utility boxes, to search in the streets around the site.