Iran's supreme leader Ayatollah Ali Khamenei on Sunday accused the United States of trying to retake control of Iraq by exploiting sectarian rivalries, as Sunni insurgents drove toward Baghdad from new strongholds along the Syrian border.
Iran's condemnation of US action in Iraq came three days after President Barack Obama said he would send 300 'military advisers' to Iraq in response to pleas from Iraq's government for US military support (See: Obama set to send 300 US 'military advisors' to Iraq ).
Khamenei's comments ran counter to speculation that the US and Tehran might patch up their differences and cooperate to defend their mutual ally in Baghdad, after two weeks of swift territorial gains by Sunni Islamists.
On Sunday, militants overran a second frontier post on the Syrian border as the Islamic State of Iraq and the Levant (ISIL) pursues the goal of its own caliphate straddling both countries.
"We are strongly opposed to US and other intervention in Iraq," IRNA news agency quoted Khamenei as saying. "We don't approve of it as we believe the Iraqi government, nation and religious authorities are capable of ending the sedition."
Some Iraqi observers interpreted his remarks as a warning not to try to handpick any successor to Prime Minister Nuri al-Maliki, amid speculation he may be pushed to quit over a crisis for which many in the West hold him responsible after eight years of Shi'ite-led government has alienated minority Sunnis.
Speaking in Cairo, Secretary of State John Kerry said the United States wanted the Iraqi people to find a leadership that would represent all the country's communities - though he echoed Obama in saying it would not pick or choose those leaders.
"The United States would like the Iraqi people to find leadership that is prepared to represent all of the people of Iraq, that is prepared to be inclusive and share power," he said.
The Iranian and the US governments had seemed open to collaboration against al Qaeda offshoot the Islamic State in Iraq and the Levant (ISIL), which is fighting both the US-backed, Shi'ite-led government of Iraq and the Iranian-backed president of Syria, whom Washington wants to see overthrown.
"American authorities are trying to portray this as a sectarian war, but what is happening in Iraq is not a war between Shi'ites and Sunnis," said Khamenei, who has the last word in the Islamic Republic's Shi'ite clerical administration.
Accusing Washington of using Sunni Islamists and followers of ousted Iraqi leader Saddam Hussein, he added: "The U.S. is seeking an Iraq under its hegemony and ruled by its stooges."
Tehran and Washington have been shocked by the lightning offensive, spearheaded by ISIL and involving Sunni tribes and Saddam loyalists. It has seen swathes of northern and western Iraq fall, including the major city of Mosul on 10 June.