BAGHDAD - Talks between the United States and Iran this month will be an opportunity for Tehran to enter a "whole new era" in relations with Iraq, but first it has to stop aiding Iraqi insurgent groups, the U.S. envoy leading the discussions said yesterday.

Iranian and American officials said the talks, beginning May 28 in Baghdad, would be limited to the security situation in Baghdad and would not delve into the diplomatic deadlock between the two countries over Iran's nuclear program.

"It is not about U.S.-Iranian relations," said Ryan Crocker, the U.S. ambassador to Iraq, who will lead the American delegation. "It's about how direct contact between us can help the situation inside Iraq."

Iran and the United States have not had public bilateral meetings on a specific issue since Washington broke off relations with Tehran over the 1979 embassy hostage crisis. Previous encounters have been at multilateral gatherings. The two countries held talks under U.N. auspices between 2001 and 2003 regarding Afghanistan, in which Crocker was involved.

The United States has accused Shiite-ruled Iran of helping train and arm Shiite militias and some Sunni insurgent groups in Iraq. It has specifically accused Iran of helping insurgents obtain explosively formed penetrators, sophisticated bombs capable of piercing armored vehicles.

The United States has "a problem with Iranian behavior in Iraq that is counter to what we want to see, what the Iraqi government and people want to see, and counter to their own stated interest," Crocker said.

Iran denies arming or financing insurgents in Iraq.

Iranian Foreign Minister Manouchehr Mottaki yesterday blamed the presence of U.S. troops for instability in Iraq.

"Terrorists say that 'we are doing this because of the foreign forces,' and the foreign forces are saying that 'we are here because of the terrorist groups,' " Mottaki told reporters in Islamabad, Pakistan, where he was attending a meeting of the Organization of the Islamic Conference.

"We do believe that a correct approach to Iraq should look to both points, or both areas of the difficulty," Mottaki said.

He said an unidentified senior diplomat would represent Iran at the May 28 meeting, which would set the agenda for more detailed discussions.

Crocker played down expectations. But he also insisted the meeting would give Iran, which fought a brutal eight-year war with Iraq that began in 1980, a rare opportunity.

"There is an opportunity here for them, I think, to move into a whole new era in a relationship with a stable, secure, democratic Iraq that threatens none of its neighbors, including Iran," Crocker said. "But to get there, they need to start doing some more constructive things than they have."