* Incident latest in military standoff
* US officials engaged to try to ease tensions
* News came after announcement Talabani in hospital
BAGHDAD, Dec 18 (Reuters) - Troops from Iraq's autonomous Kurdistan opened fire on an Iraqi army helicopter on Tuesday, underscoring tensions between Baghdad's Arab-led central government and the Kurdish region, officials said.
Iraq's government and self-ruled Kurdistan last month both sent troops from their respective armies to reinforce positions around towns in disputed areas where they both claim control as part of a broader feud over oil and territory.
Kurdistan Peshmerga officials said on Tuesday they fired on an Iraqi military helicopter near Sikanyan town just north of the ethnically mixed city of Kirkuk, to keep the aircraft from taking surveillance pictures of their military positions.
"We opened fire at an Iraqi military helicopter flying over our forces," said Anwar Othman, deputy minister for Kurdish military affairs. "This is a clear message that next time our response will be tougher."
A local mayor in the area confirmed the incident. But there was no immediate response from the Iraqi central government.
The growing rift between Baghdad and Kurdistan is the most challenging test to Iraq's federal unity since the last American troops left a year ago, removing a buffer of U.S. military presence from an area long seen as a flashpoint for conflict.
News of the clash came just hours after authorities announced Iraq's President Jalal Talabani, a Kurd, had been hospitalized following a stroke that had left him in critical but stable condition.
A veteran Kurdish politician, Talabani has been a key mediator between Prime Minister Nuri al-Maliki's central government and the Kurdistan Regional Government who are growing further apart over how to control oil wealth and the disputed territories between their two regions.
Iraqi armed forces and Kurdish Peshmerga have faced off before only to back off before any major confrontation and U.S. officials have been in talks with both regions to try to ease tensions between them.
The ethnically mixed, disputed areas are a swathe of land separating Iraq from the territory administered by ethnic Kurds in the north, and they include the sensitive city of Kirkuk, which sits atop some of the world's largest oil reserves.
Bombings and attacks across those areas killed more than 30 people on Sunday and Monday in what authorities said was an attempt by insurgents to stoke Arab-Kurdish tensions.
Violence in Iraq has eased since the height of sectarian attacks in 2006-2007. But Sunni Islamists still carry out bombings nearly a decade after the American-led invasion to oust Saddam Hussein. (Reporting by Baghdad newsroom, Azad Lazkari in Arbil; Mohammed Ahmed in Kirkuk; writing by Patrick Markey; Editing by Stephen Powell)