Sunni extremists are likely to try a series of high-profile attacks to grab the headlines ahead of a watershed report to Congress in September on political and military progress in Iraq, the top U.S. commander said Saturday.

"We expect they will try this — pull off a variety of sensational attacks and grab the headlines to create a `mini-Tet,"' Gen. David Petraeus said in an interview with The Associated Press.

He was referring to the 1968 Viet Cong and North Vietnamese Tet offensive that undermined public support for the Vietnam War in the United States. The offensive failed to achieve most of its tactical goal but it shattered political support for the Vietnam War among the U.S. public.

Petraeus and U.S. Ambassador Ryan Crocker are to present a report to Congress by Sept. 15 on the situation in Iraq. Several Republicans say if progress is not made by then, they may call for a new strategy in Iraq.

The general would not say what he and Crocker plan to tell Congress in the report.

But he added that the two top American officials in Iraq "have a responsibility to produce our assessment of the implications" of "different options."

He would not elaborate, but other U.S. generals have warned in recent weeks against drawing down American troops too rapidly before Iraqi security forces can cope.

Petraeus would not say what measures he would take to prevent a spate of spectacular attacks. He spoke at a U.S. base, Camp Warhorse, on the edge of Baqouba, which had been the self-declared capital of the Al Qaeda front group, the Islamic State of Iraq.

On Saturday, a homicide truck bomber hit an outdoor market, killing and wounding dozens, in the Shiite town of Armili, 100 kilometers (60 miles) of Baqouba. The night before, a homicide bomber hit a funeral in a Kurdish Shiite village northeast of Baqouba, killing 22.

The attacks suggested Al Qaeda militants and other Sunni insurgents have moved further north, to avoid U.S. troops and strike where security is weaker.

U.S. troops have gone on the offensive in Baqouba, 55 kilometers (35 miles) northeast of Baghdad and have gained control of the western half of the city.

U.S. forces have also launched an offensive in areas south of Baghdad, where Al Qaeda and other Sunni insurgents are believed to rig car bombs that strike in the capital.

If U.S. troops can drive the extremists away from strategic areas around Baghdad, they hope to minimize attacks in the capital that draw international attention.

Petraeus said there had been progress in restoring stability in some areas of the country, notably Anbar where Sunni sheiks have turned against Al Qaeda. Last weekend, U.S. troops killed 35 insurgents in what commanders believe was an attempt reinfiltrate Ramadi, the Anbar provincial capital, where extremist attacks have dropped sharply.

At the national government, however, reconciliation efforts among Sunni, Shiite and Kurdish politicians have faltered because of deep differences on power-sharing. Some of the issues, including sharing oil wealth and regional powers, are at the core of the Iraq conflict.

Last year's wave of sectarian killings, which escalated after the February 2006 bombing of a Shiite mosque in Samarra "really tore the fabric" of Iraqi society, Petraeus said.

"At the national level, progress to foster true reconciliation is still a work in progress," Petraeus said. "In some respects we should recognize that these issues are fundamental, that they are doing it in an environment shaped by very bad sectarian violence" last year.