(Adds details, background, quotes)
By Arshad Mohammed and Parisa Hafezi
WASHINGTON/VIENNA, June 16 (Reuters) - U.S. and Iranian officials discussed the crisis in Iraq on the sidelines of separate negotiations about the Iranian nuclear program in Vienna, three sources familiar with the matter said on Monday.
Militants from the Islamic State of Iraq and the Levant group have routed Baghdad's army and seized the north of the country in the past week, threatening to dismember Iraq and unleash all-out sectarian warfare with no regard for national borders.
U.S. President Barack Obama will review his national security team's suggestions for how to deal with the crisis in Iraq, including possible actions, when he returns to Washington later on Monday, the White House said earlier.
"The disastrous situation in Iraq was discussed today. No specific outcome was achieved," a senior Iranian official told Reuters of the talks on Iraq. "Iran is a great country that can play a key role in restoring stability in Iraq and the region."
"Military cooperation was not discussed and is not an option," the senior Iranian official added. "The final decision will be taken by capitals."
Officials from Iran and six major powers are meeting in Vienna this week to see if they can meet a July 20 deadline to secure a comprehensive agreement to limit Iran's nuclear program in exchange for removing Western sanctions on Tehran. (Reporting by Arshad Mohammed and Parisa Hafezi; Editing by Peter Cooney)