By James Shaw

BBC News, Baghdad



Iraqi police said the helicopter had been shot at from the ground

The attack took place in Diyala province north-east of Baghdad, the sources say.

A spokesman for the US military said there had been helicopter activity in the area but he was not able to confirm any other details.

The school is in the village of al-Nedawat close to the Iranian border.

Investigation

One police officer said the helicopter was shot at from the ground during the morning.

The school was said to have been hit when the aircraft returned fire.

The officer said police had spoken to eyewitnesses and that six children had been killed and six injured but the figures have not been independently confirmed.

A spokesman for the US forces in Iraq, Lt-Col Chris Garver, said the US tried to do everything possible to avoid civilian casualties, which was why it was taking the reports seriously and conducting an investigation.

There has been an escalation of violence in Diyala in recent weeks.

On Sunday, a convoy of US armoured vehicles was hit by a bomb which killed six soldiers and a Russian journalist who was travelling with them.