By Jonathan Allen

NEW YORK (Reuters) - Relatives of September 11 victims still confronted with the loss of their loved ones are fighting plans to place unidentified remains in a repository carved into the bedrock below the World Trade Center site.

The underground vault, already under construction, will house unidentified remains and be accessible only to staff of New York City's chief medical examiner's office, which will continue to attempt to identify the remains as technology improves.

The space will be adjoined by a small private room for the exclusive use of victims' families, who will be able to see into the repository -- a working laboratory as much as it is a tomb -- through a window.

The area will be sealed off from the memorial museum that will fill the rest of the mostly subterranean structure. Visitors will see only a wall bearing a quotation from Virgil's epic poem "Aeneid" wrought in steel salvaged from the fallen towers: "No day shall erase you from the memory of time."

Officials from the National September 11 Memorial & Museum Foundation say the arrangement was arrived at following extensive consultation with victims' families over the past decade.

But some families in the minority are upset at what they say was an undemocratic process and find the placement of the repository within the museum structure disrespectful, revealing how the topic of 9/11 remains fraught with emotion a decade after the attacks.

"The idea of putting the remains in a museum is just a barbaric and incomprehensible insult and really it shocks the conscience," Sally Regenhard said in an interview, describing the museum as a "macabre Ripley's Believe It or Not."

She said the unidentified remains should be interred in a "tomb-like" structure at ground level, akin to the Tomb of the Unknowns at Arlington National Cemetery. She disagrees with the museum's position that the Virgil-inscribed wall is sufficient for the repository to be considered "distinct" from the museum, as per guidelines drawn up in consultation with families in 2003.

Jim Riches, whose firefighter son, Jimmy Riches, was killed in the attacks, criticized what he called the "marketing of the dead," citing as an example a keychain that will be sold in the museum store bearing the Virgil quotation.

"It's disgusting," he said.

More than 2,700 people were killed at the World Trade Center in 2001 when al Qaeda hijackers crashed passenger planes into the Twin Towers.

An above-ground memorial was opened to the public last September 11 and two of the four planned skyscrapers for the site are well into construction. The underground museum was due to open in September this year but will be delayed due to financing problems.

While many families have received the partial remains of their spouses or children, allowing them to conduct a funeral service, some 1,100 families have received nothing.

The city's chief medical examiner has custody of the unidentified remains, which are currently stored in temporary structures in a parking lot near the morgue in Manhattan. The unidentified remains are the only focal point many families have for their loss.

Regenhard, whose firefighter son, Christian Regenhard, was killed in the attacks, belongs to one of the 17 families who unsuccessfully sued the city last year in an attempt to force officials to solicit feedback from victims' families. The city argued feedback had already been sought on multiple occasions.

The families say they plan to appeal the decision this year and are calling for congressional hearings to establish a protocol for handling human remains in the wake of disasters or attacks.

Members of those families recently e-mailed an informal survey to about 2,100 members of victims' family, asking if they approved of the city's plans. The group announced the results at the weekend: 350 people responded, with 332 people, representing 298 families, saying they disapproved, according to their lawyer, Norman Siegel.

Before posing the question, the e-mail said family members would have to pass by the museum's souvenir store and snack bar "along with thousands of tourists" to access the repository.

Officials from the museum say this characterization is wrong, and that family members will have use of a private room overlooking the memorial fountains at ground level, and will be escorted directly down to the repository, and that they can visit outside museum hours.

"Since the very beginning, victims' family members have strongly advocated for the unidentified remains to be returned to the World Trade Center site," Joseph Daniels, the president of the memorial and museum foundation, said in a statement.

Charles Wolf, whose wife, Katherine, was killed in the attacks, said the comments made by some members of the 17 families were inflammatory and misleading, and that there was "near unanimity" among victims' families to "repatriate" unidentified remains to what he called "sacred bedrock."

"They've bent over backwards to accommodate us," Wolf said of the memorial foundation staff. "Everything they said would happen has happened."

(Editing by Daniel Trotta)