A police officer from the strife-hit US city of Ferguson has been shot and the suspect is still at large, law enforcement officials have said.

The officer was chasing two suspects outside the Ferguson Community Center on Saturday night when one turned and shot him in the arm, St. Louis County Police Chief Jon Belmar told a news conference.

The officer, who is expected to survive, returned fire but apparently did not hit either suspect, Belmar said.

"I wouldn't have any reason to believe right now that it was linked in any way, shape, manner or form with the protests," he said.

The Missouri Department of Public Safety said that a search was under way for the suspect in the shooting, adding that the incident took place at a community centre slightly removed frmo the main protest areas.

Ferguson, St Louis suburb, saw days of racially charged protests after African-American teenager Michael Brown was shot dead by a Caucasian police officer, Darren Wilson, on August 9.

A crowd of about 100 people gathered near the scene of the shooting, with a group breaking off to stage a protest at the Ferguson police headquarters, according to Kareem Jackson, 27, who is a member of the activist group HandsUp United.

"People are peaceful as a duck, just literally standing on the side of the street watching," he told Reuters in a phone interview from the site where protesters had gathered.

On Thursday, Ferguson police chief Tom Jackson issued a video apology to Brown's parents following weeks of heavy criticism and calls for his ousting.

The apology was not well-received among some and led to reported protests hours after it was issued.

Since Brown's death, there have been outbreaks of violence during weeks of protests in Ferguson, a predominantly African-American community of 21,000.

Many have called for Jackson to be fired for what they saw as a heavy-handed response in the aftermath of the killing.

The Reuters news agency reported that police have set up roadblocks in the area of Saturday's shooting, and police searched the area for the two suspects.

Source: Agencies