Blood-splotches on walls, chains hanging from a ceiling and swords found on the killing floor of a suspected Al Qaeda in Iraq torture chamber are the latest horrors discovered by U.S. soldiers pushing into a province that remains an extremist stronghold.

Scrawled in white paint on one wall above a bed used for torture was a Quranic phrase normally used to welcome a guest, but given the horrific surroundings, conveyed only sadistic mockery: "Come in, you are safe" was the message in Arabic.

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The filthy dirt floor of the torture complex — found near nine mass graves containing the remains of 26 people — was littered with food wrappers, plastic soda bottles and electric cables that snaked to a metal bed frame, presumably where detainees were shocked.

Villagers nearby knew about the torture complex, but did not tell authorities as they were afraid of reprisals from the militants, a local policeman on Thursday told The Associated Press on condition of anonymity as he was afraid of being targeted by extremists. He said he thought the chamber had been used for a year.

It was information from Iraqis, the military said, that did finally lead them to the site.

"We discovered several (weapons) caches, a torture facility that had chains, a bed — an iron bed that was still connected to a battery — knives and swords that were still covered in blood as we went in to go after the terrorists in that area," said U.S. Army Maj. Gen. Mark P. Hertling, the top U.S. commander in northern Iraq.

It was not the first such torture chamber discovered in Iraq, and it was a stark reminder of the horrors that exist in this country after nearly five years of war, despite growing optimism as violence has fallen about 60 percent since June.

The U.S. military — which discovered the torture site, along with nine weapons caches during a Dec. 8-11 operation north of Muqdadiyah, about 60 miles north of Baghdad — said it was used by Al Qaeda in Iraq. Graffiti on the building proclaiming "Long Live the Islamic State" has been used by the insurgent group in the past. Their stated goal is to establish such a state, or caliphate, in Iraq.

Diyala province, where the grisly discovery was made, remains turbulent, largely because militants were pushed north into the area after the summer influx of U.S. troops into Baghdad, and east from Anbar province after anti-Al Qaeda Sunni groups there grew in strength.

The province is mixed between Sunnis and Shiias, a microcosm of what Iraq was before sectarian bloodletting largely partitioned many parts of the country along religious lines. Diyala's residents refer to it as "a little Iraq" — which makes fueling sectarian violence there an easier task.

"I think that is why Al Qaeda wants that province so very much, because it is 'a little Iraq,"' Hertling said. "It gives them access to Baghdad and it also ... is considered their caliphate capital."

Both Sunni insurgents and Shiite militia death squads regularly torture their captives before killing them — often with power drills. Most of the hundreds of bodies that have turned up in Baghdad and other parts of Iraq have had signs of torture.

In March, U.S. troops discovered a similar site in the village of Karmah just west of Baghdad that was used by Sunni insurgents for torture and summary executions. They rescued two Iraqi captives, who apparently had been spared immediate execution because the militants' video camera broke and they wanted to film the killing.

The captives told U.S. soldiers they had been convicted to death by an insurgent court and had the choice of either beheading or a fatal gunshot.

As U.S. and Iraqi troops continue to carry out strikes in Diyala and push deeper into a province that includes areas never controlled by coalition forces, the discovery of more torture sites may occur.

Despite any progress made in Diyala, American commanders are the first to say they are a long way from declaring victory.

The nine weapons caches troops also discovered — containing a surface-to-air missile launcher, sniper rifles, and 130 pounds of homemade explosives among other weapons — points to an insurgent group that is still lethal, Hertling said.

Asked if he is confident his troops can safeguard territory gained and projects it has recently completed — such as a temporary bridge to replace one blown up by insurgents — Hertling was cautious.

"You know, there's going to be continued spectacular attacks," he said. "Are we confident we can protect it? As soon as I say, 'yeah, we're confident," it's going to blow tomorrow."

Meanwhile, a homicide bomber northeast of the capital and a car bomb in Baghdad Thursday shattered the calm of an otherwise unusually peaceful holiday period in Iraq. Authorities said 19 people were killed in the two attacks, including a U.S. soldier.

Despite the bombings, this year's holiday period has been markedly calmer compared to the same time last year, when at least 80 Iraqis were killed on the first day of Eid al-Adha, one of the most important holidays of the Islamic calendar which commemorates the prophet Abraham's willingness to sacrifice his son for God.

So far this month, 536 Iraqis have died in war-related violence — compared to 2,309 in December last year, according to an Associated Press count.

Violence across the country has fallen by about 60 percent in recent months — a drop largely attributed to a combination of this summer's increase in U.S. troops in Baghdad, a freeze on activities by the Mahdi Army militia and the appearance of "awakening councils" — Iraqi Sunni tribesmen who have turned against Al Qaeda in Iraq.

In Washington, U.S. President George W. Bush said that more work remains to be done in Iraq, especially in terms of political improvements in the country.

"Are we satisfied with progress in Baghdad? No, but to say nothing is happening is not the case," Bush said.

The bomber struck in Kanaan, a Shiite-dominated town near the city of Baqouba in Diyala province, about 35 miles northeast of Baghdad. He detonated his explosives as a U.S. patrol was about to enter a building where a city council meeting was to be held, the U.S. military said.

The U.S. military said one soldier and five civilians were killed, and that 10 more soldiers and one Iraqi were wounded; however, local police and the hospital morgue in Baqouba said 13 eople were killed at the scene. An official with the morgue, who asked not to be identified as he was not authorized to release the information, said one more person later died of his injuries, bringing the total to 14.

The discrepancy could not immediately be reconciled. It was unclear how many Iraqis were wounded in the attack. The assistant police chief of Kanaan, Capt. Waleed Mitieb al-Karkhi, said they included three children and two women.

In Baghdad, a car bomb killed four people and wounded another nine outside a store selling liquor in the center of the city, police said.

But much of the day's violence was centered in Diyala province, where turbulence has been slower to subside than other parts of Iraq and which includes areas that the U.S. military has never controlled.

The top U.S. commander in northern Iraq — whose area includes Diyala — has warned that Al Qaeda in Iraq is still capable of staging spectacular attacks there despite a 50 percent drop in violence in his region.

Army Maj. Gen. Mark P. Hertling said Wednesday that Al Qaeda in Iraq was being pushed north by the increased number of U.S. troops that surged into Baghdad over the summer and fall. The U.S.-backed "awakening councils" have also been flushing insurgents out of the neighboring Anbar province.

Many of the insurgents have passed through Diyala, Hertling said. "There are still some very bad things happening in that province, but we are continuing to pursue Al Qaeda so they don't find a safe haven anywhere."