SAN FRANCISCO (Reuters) - The mayor of Oakland, California, said on Wednesday she had moved to fire four police officers and suspend seven more in connection with a sex scandal that has roiled the department in recent months.

The Oakland Police Department has been racked with problems, including the resignation of three police chiefs in quick succession after news of the scandal involving a teenage sex worker and police officers emerged in local media in June.

"We believe we have taken very strong and serious discipline, and that it sends a very loud message about what our expectations are for the conduct and professionalism of police officers," Mayor Libby Schaaf told the evening news conference.

Oakland City Administrator Sabrina Landreth said the city issued notices of intent to discipline 12 officers in total on Wednesday.

The city is seeking to terminate four officers over violations including attempted sexual assault, engaging in lewd conduct in public, assisting in the crime of prostitution, accessing law enforcement databases for personal gain, failing to report a violation of law, and lying to investigators, she said.

The city issued notices of intent to suspend seven other officers without pay, and intends to order counseling and training for another officer, Landreth said. She said the proposed disciplinary actions were subject to due process and grievance processes.

Representatives for the Oakland Police Officers' Association could not be immediately reached for comment. But the organization expressed anger over the allegations in June, saying they "do not represent what we stand for."

Schaaf added that prosecutors were investigating the case and she expected a decision on possible charges to be made "relatively soon."

Schaaf declined to provide the identities of the officers involved and other details about the investigation.

The East Bay Express newspaper reported in June that as many as 21 officers from the Oakland Police Department and other area law enforcement agencies had sex with a teenage sex worker, including some incidents while she was underage.

The newspaper based its report on interviews with the woman, elected officials, Oakland police sources and documents. Other media outlets have since published similar accounts.

(Reporting by Curtis Skinner in San Francisco; Editing by Peter Cooney)