NEW YORK - The renewed search for human remains around the World Trade Center site is so massive, the city plans to hire several more forensics experts.

Up to 10 forensic anthropologists will join the effort to find remains of Sept. 11 victims, a project that could stretch well into next year, Deputy Mayor Ed Skyler said Wednesday.

"We will make sure we have the appropriate resources to do this job," said Skyler, who is overseeing the recovery. "The mayor's orders were very clear: 'Do what needs to be done.'"

Meanwhile, the families of Sept. 11 victims planned to rally at ground zero on Thursday to call for federal intervention, a greater expansion of the remains search and a more clearly defined organization of the effort.

"Hiring extra anthropologists is a recognition that they realize the job they have to do," said Charles Wolf, whose wife was killed on Sept. 11. "But doing the job and doing it right are two different matters. How are you going to manage this?"

The current search was prompted by the discovery last month of human bones in an abandoned manhole.

Some 200 pieces of bone and other remains have been found since the accidental discovery by utility workers doing routine labor along the western edge of the lower Manhattan site.

Officials have said the manhole had been paved over and forgotten when a service road was built there in the midst of excavating trade center rubble years ago.

After the discovery, city officials identified about 10 more manholes and pockets under the road and ordered them to be excavated immediately and sifted for remains.

The work involves tearing up parts of side streets, exploring the rooftops of selected buildings near the 16-acre site and excavating more manholes beyond the dozen the city is already exploring.

Some families have pushed for the city to bring in the Joint POW/MIA Accounting Command, a military forensic unit that specializes in finding soldiers who went missing long ago.