A homicide car bomber killed seven people at a Green Zone (search) checkpoint early Tuesday, the second attack in two days near the same gate into the district that houses Iraq's interim government and the U.S. Embassy, officials said.

Meanwhile, Prime Minister Ayad Allawi (search) said the trial of some of Iraq's former Baath Party (search) leaders will begin next week. He didn't say that Saddam Hussein (search) would be among them.

Elsewhere in Baghdad, the chairman of the Joint Chiefs of Staff announced the U.S. military will have a record-high 150,000 troops in Iraq through the Jan. 30 elections and "a little bit after."

Tuesday's blast at the Green Zone checkpoint killed seven people and wounded at least 13 people, said Dr. Hassan AbdelSatar from Baghdad's Yarmouk Hospital.

Police Lt. Rafid Abid said the attack was carried out by a homicide car bomber.

A mushroom-shaped cloud of black smoke rose from the site of the attack, which was near where a bomber struck Monday, killing 13 and injuring 15 people. The location is near the Harthiyah gate on the western edge of the zone, which has been repeatedly targeted by bombings and mortar and missile attacks since it became the headquarters of the occupation authorities in May 2003.

No U.S. troops were injured in either blast.

The U.S. Embassy and several other missions are located inside the zone, which occupies an area of four square miles on the west bank of the Tigris River. The area, comprising Saddam's palace and other administrative buildings, is a virtual fortress encircled by miles of 12-foot-high barricades, its gates guarded by U.S. Bradley fighting vehicles. The complex is off-limits to the public.

Several of Baghdad's main arteries dead-end straight into it, cut off by a triple layered sprawl of concertina wire, impassable concrete blast walls and sandbagged guard towers.

In other violence, the U.S. military said two U.S. Marines from the 1st Marine Expeditionary Force based in western Iraq died in combat in Baghdad province Monday, bringing the number of Marines killed to 10 in three days.

Seven other Marines died in action Sunday in Anbar (search), a vast province west of Baghdad including the battleground cities of Fallujah and Ramadi, and a 10th was killed Saturday. The military provided no details on their deaths, which brought to nearly 1,300 the number of American troops killed in Iraq since the invasion in March 2003.

Gen. Richard Myers, the chairman of the Joint Chiefs of Staff, said U.S. troop numbers will rise from 138,000 to 150,000 before next month's elections, which many Iraqis fear could be targeted by militants opposed to the occupation and bent on derailing the political process.

"Our troop levels will be at 150,000 for the elections and a little bit after," Myers said.

Asked when exactly the troops would pull out, he responded: "That will be determined by events on the ground."

The previous high for the U.S. force in Iraq was 148,000 on May 1, 2003, when President Bush declared that major combat operations were over and most soldiers thought the war had been won. The initial invasion force included thousands of sailors on ships in the Persian Gulf and other waters, plus tens of thousands of troops in Kuwait and other surrounding countries.

Poland said Tuesday it will cut its troop strength in Iraq by nearly a third in the month following the vote, as part of long-standing plans to reduce its presence. Poland's current 2,400-member contingent will be cut to 1,700 from mid-February, with 700 soldiers remaining in Poland on standby, Defense Minister Jerzy Szmajdzinski told a news conference in Warsaw.

Myers predicted that last month's U.S.-led offensive to retake the western militant stronghold of Fallujah would undercut the insurgency by denying guerrillas a sanctuary from which they could launch attacks with relative impunity.

"They will try to move to other locations but I don't think they are going to find any location as satisfactory as Fallujah was for their operational planning and facilitation of what they were doing."

Despite repeated forecasts in the past that successes on the battlefield and the arrests of most of Saddam's top aides would weaken the insurgency, the number of attacks on U.S. troops and the interim government's security forces has not decreased.

About 550 U.S. soldiers died in the first year after the invasion was launched; almost 750 troops have died in the nine months that followed.

Myers is in Iraq for a morale-boosting holiday visit to the troops with celebrities including actor Robin Williams (search), former Denver Broncos quarterback John Elway (search) and sportscaster and model Leeann Tweeden (search). The VIPs were greeted at Camp Liberty west of Baghdad by the cheers of soldiers representing units including the 1st Cavalry Division based Germany, the 256th Brigade of the Louisiana National Guard and the 2nd Brigade of the 10th Mountain Division out of Fort Drum, N.Y.

The announcement by Allawi on proceedings against figures from the former regime was the latest in several conflicting accounts from officials about when the trials before the Iraqi Special Tribunal would begin. They have also said that Saddam might not be the first to be tried.

Many members of the former regime have been in jail for more than a year, and so far, few have been able to meet with counsel. Saddam's Jordan-based lawyers say they have not seen the former dictator, arrested a year ago Monday.

"I can now tell you clearly and precisely that, God willing, next week the trials of the symbols of the former regime will start, one by one so that justice can take its path in Iraq," Allawi told the interim National Council, without saying who would be tried.

Saddam and his 11 top lieutenants have been held for months in an undisclosed location, believed to be near the Baghdad International Airport, west of the capital. They appeared before the special tribunal in July to face preliminary charges from the former regime.

Also in Baghdad, unidentified gunmen shot to death Mousa Jabar, a commander in the al-Mahdi army of firebrand anti-U.S. cleric Muqtada al-Sadr (search), officials said. Jabar was killed in a drive-by shooting in Baghdad's Sadr City, a stronghold of the militia group.