The State Department confirmed on Wednesday that the United States has been discussing with Iran its efforts to combat the Islamic State (IS) terror group in Iraq.

The discussions have taken place in the past several weeks, most recently on the sidelines of the latest round of nuclear negotiations in Vienna two weeks ago, according to State Department Spokeswoman Marie Harf.

Confirmation that the United States and Iran are engaged in conversations about IS (also known as ISIL or ISIS) comes amid reports that Iran has launched air strikes against IS targets in Iraq, a move that has led to speculation that the Obama administration and Tehran are coordinating more closely than first thought.

Asked on Wednesday to reveal the last time the United States and Iran had any sort of discussions about the anti-IS fight, Harf confirmed that such conversations had taken place "on the sidelines" in Vienna.

"That’s the only place we have raised it," Harf said during the State Department’s daily brief. "I’m guessing—I’m assuming it came up during the last round we had."

The issue of U.S. operations against IS "frequently" comes up between U.S. officials and Iranian ones during the nuclear talks, Harf said.

"It frequently does" get raised, Harf said. "I mean, it would be odd if we were all in a place for two weeks and it didn’t come up."

However, these discussions have not taken place between U.S. and Iranian officials located in Iraq, Harf said.

The setting of the nuclear talks is "the only place we have discussed with the Iranians" the anti-IS fight, she said.

The Iranians continue to deny that such conversations are taking place, and insist that there is no coordination with the United States in Iraq.

"No change has happened in the Islamic Republic of Iran's policy of campaign against Takfiri groups, assisting the Iraqi government and presenting consultations on the fight against terrorist and Takfiri groups, and the news about Iran's cooperation with the military groups of other countries in the war on ISIL is not true," Iran’s Foreign Ministry said on Wednesday, according to reports in Iran’s state-controlled media.

"We deny the news reports on military cooperation," according to Iran’s Foreign Ministry spokesman.

Iran also denies that it has launched airstrikes on IS in coordination with the United States.

Iran will never partner with U.S. coalition forces because it blames the West for IS’s rise, according to Iranian military officials.

"The Islamic Republic of Iran blames the United States as the root cause of unrests and problems as well as the terrorist actions of ISIL in Iraq," one Iranian military leader was quoted as telling the Fars News Agency.