Iran is no longer willing to ship its nuclear materials out of the country on Sunday, a move that was to be a critical component of a proposed agreement in a deal to prevent it from building nuclear weapons.

Tehran initially agreed that it would export a large portion of its uranium stockpile, which it spent years and billions of dollars to collect, to Russia, one of the six other countries involved in the negotiations to prevent its usage in future weapons programs.

However, with less than 48 hours to go to reach an agreement, Iranian officials have reversed their position, the New York Times reported Sunday night.

"The export of stocks of enriched uranium is not in our program, and we do not intend sending them abroad," the official, Abbas Araqchi, said, according to Agence France-Presse. "There is no question of sending the stocks abroad."

"There are other solutions to create trust," Araghchi told Bloomberg. "We are towards the end of the negotiations, the negotiations are very tough right now, and the percentage chance of a deal changes after every meeting."

This story originally published at 9:43 p.m. and has been updated since then.