An Iraqi military helicopter crashed Wednesday near a major oil refinery that is a frequent target for jihadists, killing the crew, a senior officer said.

The cause of the crash near Baiji, around 200 kilometres (120 miles) north of Baghdad, was not immediately clear, according to the army colonel.

But residents in Seiniye, where the helicopter went down, said it had been hit by jihadist fighters.

"The helicopter was on its way back from Baiji. The entire crew was killed," the officer said, without specifying how many died in the crash.

A resident, who said the incident occurred at around 9:00 am (0600 GMT), described the helicopter as "completely charred".

Iraqi federal forces have been battling the Islamic State group at the Baiji oil refinery since the beginning of the jihadist offensive in early June.

Another Iraqi helicopter, a Russian-made Mi-35, was shot down in the same area on October 3. The defence ministry said at the time it was launching an investigation into the incident.