In a distinct change in position, Peruvian officials announced Wednesday that they are now seeking the prompt return of all the Inca artifacts currently housed at Yale.

For over six months, both Yale and Peruvian government representatives have maintained that any final agreement between the parties would closely resemble a memorandum of understanding signed in New Haven in September. But a provision in the memorandum that stipulated that some artifacts would remain at Yale for up to 99 years is no longer acceptable to Peru, government officials told the News on Wednesday.

Instead, while Peruvian authorities continue to cite an interest in a research collaboration with Yale, they said they would like that interaction to begin after the artifacts return to Peru.

The pieces have been at Yale for just under a century; Yale explorer Hiram Bingham III excavated them from Machu Picchu between 1911 and 1915, and they have remained at the Peabody Museum of Natural History ever since.

If Peru has its way, though, the objects will soon leave Yale.

“Peru is making a counterproposal to Yale to have all of the over 46,000 pieces sent to Peru,” said Vladimir Kocerha, a spokesman for the Peruvian government. “There will also be an agreement between Peru and Yale by which Peru then temporarily returns to Yale some pieces to be studied.”

William Cook, who represents Peru in the negotiations and is a lawyer with the Washington, D.C., law firm DLA Piper, said in a phone interview Wednesday night that the Peruvian government made its stance clear in a letter to the University last week. He declined to elaborate on the proposal’s contents, pending a response from Yale.

University General Counsel Dorothy Robinson could not be reached for comment Wednesday night. But in an e-mail to the News on Monday, she confirmed receipt of the letter from Peru and said she remains optimistic that the negotiations will yield an “amicable resolution.”

“We are reviewing the document sent to us,” Robinson said. “[The memorandum] is a balanced solution that creates a collaboration. It was agreed to by both sides and should continue to guide the outcome.”

The memorandum called for a final agreement to be completed within 60 days. But over half-year since it was signed, there are still no clear signs that the nearly century-long dispute will end any time soon.

Peru’s lead negotiator, Minister of Health Hernan Garrido-Lecca, signed that memorandum on Sept. 14 of last year. But in a press conference in Peru and written statement to the News on Wednesday outlining the country’s new position, Garrido-Lecca showed just how much has changed since his visit to Yale in the fall.

Yale officials have long said that political strife in Peru has stalled the final agreement. And it was that political pressure that in part spurred the change in Peru’s stance in the negotiations, according to a Peruvian official familiar with the negotiations who declined to be named because of confidentiality restrictions.

“There’s been a lot of pressure in Peru about this issue recently,” the official said. “So of course, the government is going to respond.”

Perhaps the most prominent opponent to the memorandum was Eliane Karp de Toledo, the former first lady of Peru who in February penned a piece in The New York Times condemning the memorandum’s terms.

In a testament to her strong feelings on the issue, Karp de Toledo said in a Wednesday interview that the new Peruvian position does not go far enough in spelling out Peru’s rights.

“It’s a big change, absolutely,” she said. “But it’s not enough. Condition number one has to be the immediate recognition of Peru’s claim to all the property and the immediate return of it all.”

“All the property” is a phrase that would normally not be controversial. But since the Peruvian government announced the findings of a March inventory it conducted of the objects on a visit to Yale, the size of the collection has been the focus of much scrutiny.

On Sunday, Garrido-Lecca said Peru found over 40,000 pieces at Yale. Wednesday, that number was more precise: 46,332. The number of lots — or groups of artifacts — in the collection, according to Peru, is 5,728.

Yale had previously announced that there were over 4,000 Inca lots at the Peabody. But archaeology professor Richard Burger, who conducted a preliminary inventory of the objects earlier this year, said there is no substantive difference between the figures.

“It’s just a different way of counting the same objects,” he said. “They don’t know of anything that I don’t know of. This whole thing about the numbers seems to me just confusion that’s being introduced needlessly.”

University spokesman Tom Conroy could not be reached for comment late Wednesday night. But Burger, who is on an archaeological expedition in Peru, provided his description of these negotiations in clear terms.

“It’s been like a game of ping-pong,” he said.