WASHINGTON (AP) — The Obama administration expects negotiations on a final nuclear agreement between world powers and Iran to begin by mid-February.

That’s according to congressional aides who were briefed by State Department and Treasury Department officials Wednesday.

They say the US and its partners are currently consulting among themselves on next steps in the nuclear talks. The group plans to meet with Iran again next month.

A six-month interim agreement partially halting Iran’s nuclear progress went into effect this week. The deal can be extended up to a year.

But the aides reported the administration is keen to begin hashing out the final agreement, which may prove far tougher. They spoke on the condition of anonymity because they were not authorized to publicly discuss the status of the talks.

Iran insists its nuclear program is for peaceful purposes, not to develop nuclear weapons.

Copyright 2014 The Associated Press.