The council voted on Tuesday 15-0 "to extend the mandate of the multinational force, as set forth in Resolution 1546 (in 2004), until December 2006".
"The unanimous adoption of this resolution is a vivid demonstration of broad international support for a federal, democratic, pluralistic and unified Iraq," US ambassador to the UN John Bolton said after the vote.
In a concession to French and Russian objections, Washington had agreed that the council would review the mandate on 15 June next year.
The resolution, sponsored by the US, Britain, Japan, Romania and Denmark, said the mandate of the force "shall be reviewed at the request of the government of Iraq, or no later than June 15 2006, and declares that it will terminate this mandate earlier if requested by the government of Iraq".
It also decided to extend until 31 December 2006 arrangements for depositing into the Development Fund for Iraq proceeds from export sales of petroleum, petroleum products and natural gas.
It said provisions for depositing those proceeds shall be reviewed at the request of the Iraqi government, or no later than 15 June 2006.
"Addressing these issues now will facilitate continued international support for Iraq's security and will give the newly elected Iraqi government time to assume office, address constitutional questions and consolidate its authority before confronting issues such as those addressed in this resolution," Bolton said.
Revenue from the oil industry,
itself a target, will go to security
Washington hopes the extension will encourage US partners to remain in Iraq and avoid a potentially tough battle in the Security Council on the mandate issue next year after the Iraqi government takes power.
The extension of the force's mandate followed an announcement on Monday by the US Defence Department of a rotation of forces that calls for the deployment of 92,000 troops in Iraq from mid-2006 to mid-2008.
They will replace a US force in Iraq that has fluctuated from a baseline of about 138,000 US soldiers. Currently, about 160,000 US soldiers are in the country as part of a temporary build-up for the 15 December elections.