* Sunni tribesmen take control of Jordan-Iraq border crossing
* Jordanian army beefs up border with more troops
* Iraqi army pulls out after brief clashes with rebels
* Jordanian officials say see no immediate threat to kingdom (Adds details, background, changes slug to IRAQ-SECURITY/BORDER from IRAQ-JORDAN/BORDER)
By Suleiman Al-Khalidi
AMMAN, June 23 (Reuters) - Sunni tribesmen took control of a border crossing between Iraq and Jordan after Iraq's army pulled out of the area following clashes with rebels, Iraqi and Jordanian intelligence sources said on Monday.
It was not immediately clear if the tribesmen's seizure of the Turaibil crossing, the only legal crossing point between Iraq and Jordan, late on Sunday was part of the broader advance by Sunni militants led by the Islamic State in Iraq and the Levant (ISIL).
The militants earlier overran posts further north along Iraq's border with Syria, pursuing their goal of forming a "caliphate" straddling both countries that has raised alarm across the Middle East and in the West.
Jordanian army sources said their troops had been on a state of alert along the 180-km (112-mile) border with Iraq for several days to ward off "any potential or perceived security threats".
Witnesses saw dozens of armoured vehicles and a few tanks on the highway heading to the Iraqi border crossing in what a Jordanian official said were reinforcements "that were sent in the last 24 hours in view of the latest developments".
Truck drivers who crossed the border into Jordan said Sunni tribesmen were now manning checkpoints along large stretches of the Baghdad to Amman highway.
The Turaibil crossing remains a major artery for Sunnis in western Anbar province and in the past two years Shi'ite Prime Minister Nuri al-Maliki has closed it several times while the Iraqi army waged security clampdowns in the region.
A security official in touch with Iraqi customs and local staff said the crossing was being operated by the usual staff who had been instructed by the Sunni tribal militants now in charge of the desolate desert area to keep it running.
Other witnesses coming from the border said Sunni tribal militants had not entered the border post with their men or vehicles but were manning checkpoints almost 35 km away, closer to the town of Rutba, 145 km east of the border with Jordan.
An Iraqi Sunni tribal leader in Anbar province involved in taking over of the border crossing contacted by phone said his group had no interest in disrupting trade with Jordan.
"This crossing is a vital lifeline for our people in Anbar who get goods and food from Jordan and we don't have an interest in scaring anyone by getting rid of the local officials and running it directly," he said.
Gains by ISIL - considered the most powerful force among armed groups who seized the Iraqi city of Falluja, west of Baghdad, and took parts of Ramadi, capital of the western Anbar province, at the start of the year - have helped it secure supply lines to Syria, where it has exploited the chaos of the uprising against President Bashar al-Assad to seize territory.
Jordanian officials say the loss of Iraqi government control over the border crossing was not seen as an immediate security threat to the kingdom, although many within its political establishment were unnerved by the prospect of al Qaeda-affiliated groups along the border.
"Jordan has the military ability to deter any attack on its territory," Mohammad al-Momani, Minister of State for Media and Communication said.
(Additional reporting by Oliver Holmes in Baghdad; Editing by Janet Lawrence)