NAJAF, Iraq (AP) – Militant Shiite cleric Muqtada al-Sadr’s militia battled U.S. and Iraqi troops Thursday in the holy city of Najaf, sparking clashes in other Shiite areas that killed at least 20 Iraqis and a U.S. soldier and raising fears of the resurgence of a Shiite rebellion.

During the daylong fighting in Najaf, a U.S. helicopter was shot down and its wounded crew evacuated. A revered Shiite shrine was also slightly damaged, witnesses said. U.S. warplanes bombed a cemetery on the outskirts of the city where militants were hiding, the military said.

After nightfall, al-Sadr’s side said it wanted to restore the truces that have kept a relative calm for months.

Al-Sadr “announced that we are committed to the truce and that (U.S.) forces must honor the truce,” Ahmed al-Shaibany, a spokesman for the cleric in Najaf, told The Associated Press. If U.S. forces do not agree, “then the firing and igniting of the revolution will continue.”

Al-Sadr’s Mahdi Army militia first rose up in April, battling U.S. and coalition troops in several cities in the first major Shiite violence against the Americans.

The confrontation dragged on for two months, until Iraqi politicians and religious leaders worked out a series of truces.

The reigniting of widescale violence now would would cause serious difficulties for coalition forces and the Iraqi interim government, already struggling against an unrelenting insurgency by Sunni militants.

Each side blamed the other Thursday for the breakdown.

“Those militias have targeted the police, so definitely our police force had to respond,” Interior Minister Falah Hassan al-Naqib said, referring to an attack on a Najaf police station early Thursday.

Ali al-Yassiry, an al-Sadr spokesman in Baghdad, accused the U.S. military of breaching the truce by fighting near al-Sadr’s house in Najaf, 100 miles south of Baghdad, on Monday.

“The Americans violated the cease-fire, and we can do nothing but defend ourselves by all means possible,” he said.

In other violence Thursday, a pair of insurgents dressed as police opened fire outside a police station while a third barreled forward in a vehicle filled with explosives and blew up, the Interior Ministry said.

The attack in Mahawil, 50 miles south of Baghdad, killed six people and wounded 24 others, the Health Ministry said. The two gunmen escaped, said Sabah Kadhim, an Interior Ministry spokesman.

In central Baghdad, insurgents fired three rockets late Friday, one of them hitting a hotel compound where foreign journalists and foreign contractors stay. The rocket hit outside a restaurant at the Palestine Hotel, leaving a small crater and shattering windows but causing no serious damage and no injuries.

Residents of Najaf called the battles in the city the fiercest they have seen. It began when Mahdi Army militants attacked a police station about 1 a.m. with mortars, rocket-propelled grenades and gunfire, officials said.

U.S. troops joined in, and the fighting continued well into Thursday night.

During the fighting, insurgents attacked a nearby U.S. military convoy, killing one U.S. soldier and wounding five others, the U.S. military said. A UH-1 helicopter was hit by ground fire and forced to make an emergency landing, the military said. The injured crew was evacuated to safety.

The fighting also slightly damaged the dome of the Imam Ali Shrine in the old city at Najaf’s center, witnesses said. The shrine – reputed to hold the remains of Imam Ali, the most hallowed saint in Shia Islam – was slightly damaged twice during fighting in May, though U.S. force have tried to avoid damaging shrines for fear of enraging Iraq’s Shiite majority.

Al-Sadr supporters took to mosque loudspeakers to call reinforcements into the streets, with al-Sadr ordering his militia to fight against any force entering Najaf’s old city, said al-Shaibany.

The Najaf violence killed seven militants and wounded 34 others, who have been detained, the U.S. military said. Nine civilians were also killed and 34 injured, including four policemen, said Hussein Hadi, an official at al-Hakeem hospital in Najaf.

In the neighboring city of Kufa, the Mahdi Army briefly took over a police station before being forced out by Iraqi police and national guardsmen, the U.S. military said.

The fighting sparked violence in other Shiite areas of Iraq.

Gunbattles broke out between militants and U.S. forces in the Sadr City neighborhood of Baghdad, killing two people and injuring two others, Health Ministry officials said. Seven U.S. soldiers were wounded, said Maj. Philip Smith, a spokesman for the U.S. 1st Cavalry Division.

In the southern city of Basra, two militants were killed in clashes with British forces on Thursday, the British military said. The Mahdi Army had threatened to attack British forces in Basra if they did not release four detained militants.

In Amarah, also to the south of the capital, an appeal for Mahdi Army members to mobilize rang out through mosque loudspeakers. Militants took to the streets, shooting at government buildings and launching mortars at British troops and a British base, said Maj. Ian Clooney, a British military spokesman. There were no British casualties and no reports of Iraqi casualties, he said.

Al-Sadr’s April uprising was sparked when the occupation government closed his newspaper, arrested a top aide and issued an arrest warrant for him for the alleged 2003 murder of a rival cleric. Hundreds died in nearly eight weeks of fighting.

Since early June there have been sporadic, low-level clashes between U.S. forces and al-Sadr’s militias. However, tension has increased in recent days however, marked by a confrontation Monday between Marines and al-Sadr’s followers.

AP-ES-08-05-04 1738EDT