Iranian officials say Inspectors from the United Nations could be allowed inside Iran’s new heavy water nuclear reactor within weeks. 

The spokesman for Iran’s nuclear department tells the official IRNA news agency Tehran is willing to grant the U.N. International Atomic Energy Agency access to its Arak reactor before the next round of talks with the agency on December 11.

But Behrouz Kamalvandi also says details of such an inspection still need to be worked out.

Iran and the IAEA signed an agreement that will allow expanded inspections of Iran’s nuclear sites.

In Vienna, IAEA chief Yukiya Amano said the agreement represents a good start.

“We have agreed to further cooperate with respect to the verification to be undertaken by the IAEA to resolve all present and past issues.”

Amano also said he still wants Iran to answer questions about its alleged nuclear weapons program, though the issue is not specifically outlined in the deal.

Iran insists its nuclear program has always been designed for peaceful purposes.

Meanwhile, Iran’s top nuclear negotiator is back home, touting progress in the most recent round of talks with Western powers over Tehran’s controversial nuclear program.

Foreign Minister Mohammad Javad Zarif sounded upbeat tone about the Geneva talks during an Iranian television talk show Monday.

“Everybody felt that considerable progress had been made. Everybody believed that there were grounds for reaching a mutual understanding and a solution, and grounds did exist. I still believe that fairly good progress was made. Let’s say if we had wanted to progress by 90 percent, we did actually progress by 70 or 75 percent.”

Zarif blamed the lack of a deal on divisions among the P5+1, the group that includes the United States, Britain, France, China, Russia and Germany.

U.S. Secretary of State John Kerry says Western powers were united in their proposal and that it was Iran, which was not ready to accept the deal.

On Tuesday, U.S. State Department spokeswoman Jen Psaki said the key point is that negotiations are going to resume next week.

“Fault is immaterial. They didn’t agree to an agreement. They’re going to come back next week and continue the discussions and continue the negotiations. We’ve narrowed the gaps. There are still issues that remain. And that’s where things stand.”