Baghdad, Iraq ? Iran is playing “a negative role” in Iraq by providing weapons, training and other support to militias and insurgent groups that interfere in Iraqi politics, the U.S. ambassador to Iraq said at a news conference on Monday.

“I have said to Iraqis that we do not seek to impose our differences with Iran on them,” Ambassador Zalmay Khalilzad said. “But we do not want Iranian interference in Iraq.”

Khalilzad also bluntly rejected recent Iranian calls for a British withdrawal from the southern Iraqi city of Basra, saying the demands were “uncalled for.” The Iranians, he said, were trying to divert attention from a recent crisis over their nuclear program by “getting involved in something that’s none of their business.”

“The coalition forces are here under a U.N. mandate at the request of the Iraqi government,” Khalilzad said. “Basra is Iraqi territory, the last time I checked the map.”

It was unclear whether Khalilzad’s remarks were a formal statement of American protest. The ambassador had concluded his comments at a news conference in Baghdad’s Green Zone on Monday morning and was heading for the exit when he spoke in response to reporters’ questions.

“I say that Iran has a mixed policy toward Iraq,” Khalilzad said. Part of that policy was a normal diplomatic relationship, he said, and the other was “to work with militias, to work with extremist groups, to provide training and weapons.” He added that there was evidence the Iranians provided “indirect help” to Sunni Arab insurgent groups as well.

The Iranian aid was part of a “comprehensive strategy,” he said, by a “player seeking regional preeminence.”

Iraq’s relationship to Iran is a complicated one. The two countries fought a brutal eight-year war in the 1980s, and many Iraqis view the neighboring Shiite theocracy with suspicion. But most of Iraq’s Shiite politicians, who will have a strong representation in the country’s new government, have close ties to Iran.

Some of the politicians maintain militias in order to back their decisions with force, and it has long been a goal of U.S. policy to disband these groups.