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BAGHDAD, Jan 28 (Reuters) - Five U.S. soldiers were killed when their patrol was hit by a roadside bomb and then came under small arms fire in the northern Iraqi city of Mosul on Monday, the U.S. military said.

The military said U.S. and Iraqi forces had secured the area following the incident, which was one of the deadliest attacks against U.S. troops in months. There were no further details.

Iraqi army and police also reported that clashes had broken out in the Haysuma neighbourhood, a known al Qaeda stronghold in eastern Mosul, Iraq's third-largest city 390 km (240 miles) north of Baghdad.

The Mosul attack against the U.S. patrol takes to 36 the number of soldiers killed in Iraq this month, up from 23 in December but similar to levels in October and November.

Mosul has been in the spotlight after Prime Minister Nuri al-Maliki said on Friday that Iraqi forces were preparing for a "decisive" offensive against al Qaeda in Iraq to push the Sunni Islamist militants out of their last major urban stronghold.

Iraqi tanks and helicopters began arriving in Mosul with troop reinforcements on Sunday.

U.S. military officials on Sunday said their own operations around Mosul were continuing.

U.S. military commanders say al Qaeda, blamed for most serious bombings in Iraq, has regrouped in northern provinces after being squeezed out of the western province of Anbar and from around Baghdad during security crackdowns last year.

(Reporting by Paul Tait, Editing by Dean Yates)

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