BAGHDAD, Iraq — Sunni Arabs are ready to end their boycott of talks to form a new government if rival Shiites return mosques seized in last week's sectarian attacks and meet other unspecified demands, a top Sunni figure said today.

Four mortar rounds exploded today on a Shiite neighborhood, killing four and wounding 16, police Maj. Moussa Abdul Karim said. U.S. helicopters fired on three houses 15 miles west of Samarra and arrested 10 people, Iraqi police said.

It was unclear if the raid was linked to Wednesday's bombing of a Shiite shrine in Samarra that triggered the wave of reprisal attacks that shook the nation last week.

Meanwhile, there was no word on the fate of Jill Carroll, an American journalist seized last month. The Sunday deadline set by her kidnappers in a message this month to a Kuwaiti television station passed without any new message from her abductors.

The Sunnis walked out of the talks Thursday after the bombing of the Askariya shrine triggered attacks against Sunni mosques in Baghdad, Basra and elsewhere. The walkout threatened U.S. plans to establish a unity government capable of luring Sunnis away from the insurgency so U.S. and other international troops can begin heading home.

Adnan al-Dulaimi, whose Iraqi Accordance Front spearheaded the Sunni boycott, said the Sunnis have not decided to return to the talks but are "intent on participating" in a new government.

"The situation is tense and within the next two days, we expect the situation to improve and then we will have talks," he told The Associated Press. "We haven't ended our suspension completely but we are on the way to end it."

He cited "some conditions" that must be met first, chief among them the return of mosques still occupied by Shiite militants in Baghdad and Salman Pak. Al-Dulaimi did not mention the other demands, but some Sunni politicians have insisted on replacing Shiite police with Sunni soldiers in heavily Sunni areas.