Smoke rises after a shell fell on a building that forces loyal to Syria’s president Bashar Al-Assad are located in, after being fired from rebel fighters in the Seif El Dawla neighbourhood in Aleppo March 28, 2015.

Iran will be invited to participate in talks in Vienna on Friday to discuss ending the conflict in Syria, a dialogue aimed at finding a framework for political transition in Damascus, the U.S. State Department said on Tuesday.

An official in the region, however, told Reuters that Iran had already been invited by the United States and Russia, and Iranian Deputy Foreign Minister Hossein Amir-Abdollahian would attend the talks, while the presence of Iranian Foreign Minister Mohammad Javad Zarif was still under discussion.

Zarif and Russian Foreign Minister Sergei Lavrov held a phone call earlier on Tuesday to discuss ways to resolve the Syrian crisis, the Russian Foreign Ministry said in a statement.

Lavrov also spoke to U.S. Secretary of State John Kerry, the ministry said.

State Department spokesman John Kirby said Kerry will travel to Vienna, and from there he will head to Central Asia for discussions with counterparts from Kyrgyzstan, Uzbekistan, Kazakhstan, Tajikistan and Turkmenistan.

Kirby said about a dozen participants were expected in Vienna for the next round of discussions on Syria. The different countries hope to eventually reach agreement on a “multilateral framework for a successful political transition in Syria which leads to a government not led by Bashar al-Assad,” Kirby said.

“There will be bilateral and multilateral discussions in Vienna on Friday and participation is very much still being worked (on),” Kirby said.

But a Western diplomat said the decision on whether to invite Iran was first discussed with Saudi Arabia, which is financing some of the militants fighting Assad and is a bitter rival of Tehran.

The White House also said that President Barack Obama and Saudi King Salman had discussed increased support for the moderate Syrian opposition in a call on Tuesday. It is unclear whether they discussed this week’s meetings in Vienna.

While Washington has opposed Iran’s support of Assad and Lebanon’s Hezbollah in Syria, it has insisted that Iran needs to be included in the talks on Syria’s future. A top U.S. military officer said on Tuesday there were fewer than 2,000 Iranian troops in Syria helping Assad’s forces.

“Iran will be asked to participate. Now, whether they come or not, that’s up to Iranian leaders,” said Kirby.

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