Police in Alameda have launched an investigation into a report that a Berkeley High School student on the boys water polo team sexually assaulted an opponent during a match last month, officials said Monday.

The investigation into the alleged incident during an Oct. 11 match at Encinal High School in Alameda is still active and no arrests have been made, said Lt. Hoshmand Durani, a spokesman for the Alameda Police Department.

It was the second time in less than a year that a Bay Area high school water polo player has been the subject of a criminal probe stemming from violence in the pool.

The latest alleged incident came to the attention of police on Oct. 12 after an Encinal school staff member told a school resource officer about it, Durani said. He didn’t go into details about the allegation, citing the juvenile status of the people involved, and didn’t know if anyone was injured.

“I don’t want to pinpoint a specific allegation because we still have to interview people,” Durani said Monday. “We have to verify all sides of the story.”

The Berkeley team’s coach, Raymond Haywood, said Monday that he had not heard about the incident or the investigation.

“This is news to me,” he said when contacted by The Chronicle. He referred other questions to the high school’s athletic director, who didn’t immediately respond to requests for comment.

On Tuesday, though, the high school’s principal, Sam Pasarow, said the coach was mistaken. He said Haywood had knowledge of the incident, but not of the investigation.

Charles Burress, a spokesman for the Berkeley Unified School District, said he couldn’t discuss what happened to the player being investigated.

“We take the issue of good sportsmanship and behavior very seriously, but we cannot comment on any specific cases of student discipline,” he said.

Last year, a 15-year-old boy from Acalanes High in Lafayette was charged with felony assault and battery for allegedly striking an opponent and breaking his nose during a junior-varsity match. Part of the incident was captured on video.

The move to charge the teen player was an uncommon instance of bringing sports violence into the criminal justice system and was sharply criticized by some.

Kimberly Veklerov is a San Francisco Chronicle staff writer. Email: kveklerov@sfchronicle.com Twitter: @kveklerov