A daylong battle Tuesday involving U.S. and Iraqi forces that saw fighter jets and helicopter gunships swooping over central Baghdad killed 50 people in a militant Sunni stronghold, officials said.

The fierce clashes came one day before U.S. President George W. Bush is supposed to announce his new strategy for the war in Iraq as the country slips further into chaos. 

Unknown gunmen ambushed this bus full of mainly Shia workers, killing nine and wounding at least 11, a hospital paramedic said.
(Asaad Mouhsin/Associated Press)

A senior defence official told the Associated Press Tuesday that the first wave of additional troops will go to Iraq by the end of the month as part of Bush's plan to send 20,000 more U.S. soldiers to the volatile country. The official requested anonymity, as the information has not yet been released.

Meanwhile Reuters news agency reported a U.S. official saying the latest draft of Bush's plan envisioned all provinces being under Iraqi control by November. 

The president is expected to address the nation at 9 p.m. ET Wednesday to outline his plan.

Planes, gunships called in as backup

Iraqi police said the battle began when gunmen attacked Iraqi army checkpoints. The army quickly called for U.S. military backup.

Witnesses said U.S. warplanes fired into the combat zone. The U.S. military said in a statement that U.S. jets buzzing the city did not conduct any air strikes, but "attack helicopters were used to engage targets in support of the ground forces."

Twenty-one militants were captured, including foreigners from Syria and Sudan, Iraqi officials said.

Revenge hangings

The battle came after more than 100 Shia civilians were kidnapped and hanged in Iraq, killings believed to be revenge for the execution of deposed leader Saddam Hussein.

Bodies were found tied to lampposts and utility poles across the embattled capital, the Daily Telegraph reported.

Witnesses said some of the attackers were Sunni.

"We have gathered 102 Shia bodies and believe 90 per cent of them were taken hostage for Saddam Hussein's execution," Capt. Mohammad Salim of Iraq's Interior Ministry told the Telegraph Monday.

The cycle of revenge comes after Saddam, a Sunni, was hanged Dec. 30 for the murder of 148 Shia Muslims in the northern city of Dujail in 1982.

A graphic, unofficial video of the hanging, captured on a cellphone, was broadcast on the internet and Al-Jazeera satellite television Dec. 31.

A second clandestine video surfaced on the internet Tuesday. It pans across Saddam's dead body, showing a gaping neck wound.

The violence that has followed Saddam's execution was particularly gruesome Sunday morning on Haifa Street in Baghdad.

The Telegraph says gunmen jumped out of three minibuses, pulling blindfolded prisoners out with them. Ropes were tied to lampposts and electricity poles and any hostages who protested were shot in the head.

The rest were hanged. Witnesses said there were 23 bodies in all.

"We are all Sunni people here, so we supported the gunmen," supermarket worker Imad Atwan told the Telegraph. "Some of them are the guards of our neighbourhood.

"Somebody called the police and the guards waited to shoot at them when they arrived …. Half an hour after the police fled, they came back with the army and took the bodies away."

With files from the Associated Press