US helicopter gunships circled low over the heart of Baghdad yesterday, firing in support of American and Iraqi troops who claimed to have killed 50 suspected militants in a lengthy battle. Explosions and heavy machinegun fire could be heard across the city after gunmen attacked Iraqi army checkpoints in a Sunni stronghold, and the Iraqis called in US backup.

The Times saw Apache attack helicopters swooping and banking repeatedly over the lawless Haifa Street district on the western banks of the River Tigris, trails of smoke rising into the air from the ground below them.

The attack came before President Bush’s expected announcement today of a surge in US troop levels and as the Shia-led Government prepares to begin the latest “Baghdad plan” to crush insurgent violence in the troubled capital.

As the violence flared, 30 people, thought to be Turkish construction workers, were killed when their aircraft crashed while trying to land in foggy weather north of Baghdad.

The chartered Moldovan Antonov-26, with about 35 people on board, crashed at about midday near the Sunni Triangle town of Balad after having aborted an earlier landing because of bad weather, the Turkish Foreign Ministry officials said.

Balad is the main US military logistics centre in Iraq, about 50 miles north of Baghdad.

In the capital itself, Major-General Ibrahim Shaker, a Defence Ministry spokesman, said that 21 militants were captured during the city centre battle, including seven foreign Arabs. “Today’s operation was designed to purge Haifa Street and nearby neighbourhoods from terrorists,” he said.

Ali al-Dabbagh, the government spokesman, said that Iraqi forces had decided to wipe out “terrorist hideouts” in the Sunni area of Haifa Street — a once-affluent district of central Baghdad housing the elegant riverside former British Embassy, frequented by T. E. Lawrence and Gertrude Bell, and the Iraqi national museum that was looted in the days after the invasion.

“God willing, Haifa Street will never threaten the Iraqi people again,” said Mr al-Dabbagh. He added that the Government had no objection to the expected increase of about 20,000 US troops.

The deployment of American aerial and armoured power in support of Iraqi troops on the ground is the model likely to be used in the Government’s proposed new plan to curb suicide bombers and insurgent attacks that have crippled political and economic progress in the country.

“The goal is to protect Baghdad and other areas. If this is going to be achieved by an increase in friendly coalition forces, we have no objection and we support this,” Mr al-Dabbagh said.

The US military said that its forces came under fire from rocket-propelled grenades and small arms during the Haifa Street operation, which lasted throughout the morning and afternoon.

Rear-Admiral Mark Fox, a US military spokesman, seeking to reassure Iraqis about the new troop surge and President Bush’s recent replacement of his Defence Secretary, two top military commanders and the US Ambassador to Baghdad, insisted: “There may be a lot of changes in leadership and there may be a lot of changes in tactics, but the relationship with our Iraqi counterparts is unchanging.”

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