Thirty people are reported to have been killed in a US-led coalition air strike in Syria, which hit an oil refinery run by the Islamic State militant group.
The Syrian Observatory for Human Rights said the dead included refinery workers and Islamic State militants.
The targeted refinery was just northeast of the town of Tel Abyad near the Turkish border.
The Islamic State group has seized wide areas of Syria and Iraq, declaring them part of a cross-border "caliphate".
The territories it controls in northern and eastern Syria include oil-producing regions that have financed the group's activities.
In November the United Nations estimated Islamic State's revenue from oil ranged from $846,000 to $1.6 million a day.
However, the Pentagon has assessed that oil was no longer the main source of revenue for the Islamic State.
Western diplomats have said this was due to air strikes on oil installations and a plunge in global oil prices that has affected black market prices as well.
