(For full coverage of Afghanistan, click on [ID:nSP508289]) (Recasts throughout with president, Afghan forces identified as security guards, more details)

KABUL, June 29 (Reuters) - The police chief for Afghanistan's southern province of Kandahar, a Taliban stronghold, and eight other officers were killed in a clash with U.S.-trained Afghan security guards on Monday, government officials said.

Afghan President Hamid Karzai said in a statement the guards were employed by the U.S.-led coalition and demanded the coalition hand them over to Afghan authorities.

No foreign troops from the coalition or from NATO-led forces were involved in the incident, said a statement released by U.S. forces in Afghanistan.

"The incident was an Afghan-on-Afghan incident, and did not involve U.S. or international personnel or equipment," it said.

The clash erupted after the guards entered the prosecutor's office in Kandahar city and forcibly removed an unidentified prisoner, said Ahmad Wali Karzai, head of the Kandahar provincial council and the brother of the president.

A gunfight erupted with police when the guards left the prosecutor's office, he said.

"The police chief for Kandahar, the head of the city's criminal department and seven other police were killed in the clash," Wali Karzai told Reuters by telephone from Kandahar.

A senior provincial lawmaker, who asked not to be identified, also confirmed the clash and said exchanges of gunfire had broken out in several other parts of the city.

Interior ministry spokesman Zemarai Bashary said police had brought the clashes under control. He told local television the prisoner had been due to appear on criminal charges on Monday.

There was no indication of any casualties among the guards.

Kandahar governor Tooryalai Weesa said the prisoner was a relative of an employee of the company for which the guards worked.

Authorities had arrested all 41 of the guards involved and the men were being sent to Kabul, he told reporters in Kandahar.

NATO forces, boosted by an influx of thousands more U.S. troops, will soon step up operations in the Taliban strongholds of Kandahar and neighbouring Helmand province, senior U.S. and NATO officials have said.

Senior U.S. military commanders have said violence in Afghanistan has reached its highest level since the Taliban were ousted after a U.S.-led invasion in 2001.

(Reporting by Sayed Salahuddin; Editing by Paul Tait)

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