A US army Black Hawk helicopter crashed in northern Italy yesterday, killing four Americans and wounding the other seven on board, officials said.

The helicopter, which according to Italian media was on a training mission, split into at least two pieces after crashing at 12.34 p.m. in a grassy field near the Italian city of Treviso. At least three of the injured were seriously hurt.

A US army spokesman could not confirm the nature of the mission, or the reason for the crash. The UA 60 flew out of the nearby Aviano air base, an important military base in Europe which deploys units to Iraq and Afghanistan, the army said.

Italian Defence Minister Arturo Parisi expressed his "solidarity" in a written message to US Defence Secretary Robert Gates.

But the incident threw the spotlight on the often controversial US military presence in Italy, where the centre-left government of Prime Minister Romano Prodi has been criticised by some allies for allowing an expansion of US military activities.

"It confirms that the Aviano military base, beyond being a threat to many people, is also a risk for local populations," said Severino Galante, a communist lawmaker whose party is part of Mr Prodi's coalition.

Fire brigade officials, who were initially alerted to the crash by a motorist driving nearby, said they were still working through the wreckage. The motorist who reported the crash was passing on a nearby highway in a town called Santa Lucia del Piave. Italian officials said they reached the site quickly, allowing them to save lives.