(Adds US officials, updates toll, context)
By John Davison and Ahmed Rasheed
ERBIL, Feb 15 (Reuters) - A rocket attack on U.S.-led forcesin northern Iraq on Monday killed a civilian contractor andinjured a U.S. service member, the U.S. coalition in Iraq said,in the deadliest such attack in almost a year.
The barrage of rockets hit in and near a military air baseoccupied by the U.S.-led coalition at Erbil InternationalAirport. Two U.S. officials said the contractor who was killedwas not American. The coalition said five other contractors werehurt, without elaborating.
The attack, claimed by a little-known group that some Iraqiofficials say has links with Iran, raises tension in the MiddleEast while Washington and Tehran explore a potential return tothe Iran nuclear deal.
Armed groups aligned with Iran in Iraq and Yemen havelaunched attacks against the United States and its Arab alliesin recent weeks, including a drone attack on a Saudi airport androckets against the U.S. embassy in Baghdad.
Most of the incidents have caused no casualties, but havekept up pressure on U.S. troops and U.S. allies in the region inthe early days of Joe Biden's presidency.
Biden's administration is weighing a return to the Irannuclear deal, which his predecessor Donald Trump abandoned in2018, that aimed to curb Iran's nuclear programme.
U.S. allies such as France have said any new negotiationsshould be strict and should include Saudi Arabia, Iran's mainregional foe. Iran insists it will only return to compliancewith the 2015 deal if Washington lifts crippling sanctions.
The U.S.-Iran tension has often played out on Iraqi soil.
A U.S. drone strike that killed Iran's military mastermindQassem Soleimani in Baghdad in January 2020 sent the region tothe brink of a full-scale confrontation.
A rocket attack on a base in northern Iraq in March lastyear killed one British and two American personnel.
Monday's rocket attack in Erbil, the capital of the Kurdishautonomous region in Iraq, was the deadliest against coalitionforces since then.
Kurdish security sources said three rockets hit around theairport and at least another two landed nearby. Reutersreporters heard several loud explosions and saw a fire break outnear the airport.
U.S. troops occupy a military base adjacent to the civilianairport. A third U.S. official, speaking on condition ofanonymity, said the U.S. service member's injury was aconcussion.
A group calling itself Saraya Awliya al-Dam claimedresponsibility for the attack on the U.S.-led base, saying ittargeted the "American occupation" in Iraq. It provided noevidence for its claim.
U.S. Secretary of State Antony Blinken said late Monday theUnited States was "outraged" by the attack.
In a statement, Blinken said he had reached out to KurdistanRegional Government Prime Minister Masrour Barzani "to discussthe incident and to pledge our support for all efforts toinvestigate and hold accountable those responsible."
Groups that some Iraqi officials say have links with Iranhave claimed a series of rocket and roadside bomb attacksagainst coalition forces, contractors working for the coalitionand U.S. installations - including the embassy in Baghdad - inrecent months.
Iraq's government under Prime Minister Mustafa al-Kadhimihas sided with the United States against Iran-aligned militiasbut has struggled to bring the powerful paramilitary groupsunder control.(Reporting by John Davison in Erbil, Ahmed Rasheed in Baghdad;additional reporting by David Shepardson in Washington; Editingby Hugh Lawson, Dan Grebler, Howard Goller, Sonya Hepinstall andGerry Doyle)