Air raid in Iraq's Mosul targets IS cash stockpile

A US-led coalition air raid has destroyed a cash storage facility used by Islamic State group militants in the Iraqi city of Mosul, a US defence official said on Monday.

Two 900-kilogramme bombs struck the facility early on Monday, destroying "millions" of dollars worth of cash, an official told AFP, speaking on condition of anonymity.

"We estimate in the millions of dollars, from all their illicit stuff: oil, looting, extortion," the official said.

CNN, which first reported the air raid, said the US military believed between five to seven civilians had been killed in the raid.

The US-led coalition carrying out plane and drone strikes against the IS group in Iraq and Syria has been increasingly targeting the militants' money-making capabilities, including by bombing trucks that ferry illicit oil across Syria.

Under pressure from critics who say the campaign is moving too slowly, the Pentagon has indicated it would consider a wider array of targets even if these might cause civilian deaths, provided these attacks yield significant gains against the Islamic extremists.

The defence official said the coalition had targeted cash-holding facilities once or twice in the past year, but the most recent action was "probably" the biggest to date.

It was not immediately clear if the money had been in US dollars, some other foreign currency, or local dinars, the official added.