Iraq has dispatched its foreign minister to Tehran with an offer to mediate in an escalating feud between Saudi Arabia and Iran, reflecting Baghdad's fears that new sectarian conflict could unravel its campaign against Islamic State.
Sunni Saudi Arabia's execution of Shi'ite dissident Nimr al-Nimr on Saturday has inflamed sectarian anger across the Middle East, infuriating Iran, the region's main Shi'ite Muslim power.
After demonstrators sacked the Saudi embassy in Iran, Riyadh and some of its allies cut off diplomatic ties with Tehran.
Iraq, where a Shi'ite-led government is urgently trying to reach out to minority Sunnis as it seeks to retake territory controlled by Islamic State militants, is particularly vulnerable to any upsurge in anger between the Muslim sects.
Powerful Iran-backed Shi'ite militia called on Iraqi Prime Minister Haidar al-Abadi - a Shi'ite who has staked his credibility on efforts to reconcile with Sunnis - to shut a Saudi embassy that reopened only last month after decades of strained ties.
Thousands of Shi'ites rallied in central Baghdad on Wednesday chanting slogans against the Saudi ruling family.
Abadi sent Foreign Minister Ibrahim al-Jaafari to Tehran to help defuse the crisis. Speaking with his Iranian counterpart Mohammad Javad Zarif, Jaafari said the row could have "wide-ranging repercussions".
"We have solid relations with the Islamic Republic (Iran) ... and also we have relations with our Arab brothers and therefore we cannot stay silent in this crisis," Jaafari told the joint press conference in Tehran.
There was no immediate reaction from Saudi Arabia to the Iraqi mediation offer.
In what militia leaders described as only an early taste of the potential for street anger, a few thousand Shi'ite demonstrators rallied in central Baghdad on Wednesday and in smaller numbers in southern Shi'ite cities.
"No, no to Al Saud! No, no to the embassy!" chanted the demonstrators who gathered on Tahrir (Liberation) Square in Baghdad, carrying the flags of the three most powerful Iranian-backed militias - Badr Organisation, Asaib Ahl al-Haq and Kataib Hezbollah.
The Saudi embassy, which reopened last month, was closed in 1990 after the Iraqi invasion of Kuwait.
Its reopening came as relations thawed under Abadi, signalling that the two countries would try to cooperate against Islamic State.
Saudi Arabia is nominally part of a US-led coalition targeting Islamic State with air strikes.
Earlier this week, Iraqi Foreign Minister Jaafari reassured his counterpart in Riyadh that the Saudi embassy in Baghdad was safe and would not meet the same fate as the embassy in Tehran.
