An Associated Press reporter in Vietnam was punched, choked and hit over the head with a camera by police who detained him Friday while he covered a Catholic prayer vigil in the communist country.

Ben Stocking, the Hanoi bureau chief for The Associated Press, was released from police custody after about 2 1/2 hours and required four stitches on the back of his head. His camera was confiscated by police.

"They told me I was taking pictures in a place that I was not allowed to be taking pictures. But it was news, and I went in," Stocking said by telephone from Hanoi.

Stocking, 49, was covering a demonstration by Catholic priests and church members at the site of the former Vatican Embassy in Hanoi, which is currently the subject of a land dispute between the church and city authorities.

The city had started to clear the site Friday after announcing a day earlier that it planned to use the land for a public library and park — a significant development in an already tense relationship between the church and state in Hanoi.

After Vietnam's communist government took power in 1954, it confiscated property from many landowners, including the Catholic Church. The church says it has documents showing it has title to the land.

Within minutes of arriving at the prayer vigil, Stocking said, he was escorted away by plainclothes police who took his camera and punched and kicked him when he asked for it back.

Taken to a police station for questioning, Stocking tried to reach for his camera and an officer "banged me on the head with the camera and another police officer punched me in the face, straight on." The blow from the camera opened a gash at the back of his head.

Transferred to another police station to give a written statement, Stocking was permitted to leave with a U.S. Embassy official to be taken to a medical clinic.

The AP is protesting the incident, seeking an apology from Vietnamese authorities involved and insisting on the return of Stocking's property.

"It is an egregious incident of police abuse and unacceptable treatment of a journalist by any civilized government authority," said John Daniszewski, the AP's managing editor for international news. "Ben Stocking was doing his job in a calm, reasonable and professional manner when he was escorted away and violently assaulted."

In Washington, State Department spokesman Sean McCormack said the Bush administration has asked the Vietnamese government what it would do to prevent such incidents in the future. The United States, he said, supports religious freedom "whether it's in Vietnam or elsewhere around the world."

U.S. Embassy spokeswoman Angela Aggeler said a formal statement of protest was filed with the Foreign Ministry.

The Foreign Ministry did not immediately respond to e-mail and telephone requests by the AP seeking comment.

Violence is rare against international journalists in Vietnam, which has strict controls that govern press activities and travel. Foreign media have to register with the Foreign Ministry and get permission to go to remote provinces.

The first portion of Stocking's arrest was captured by an anonymous cameraman and posted on YouTube.