4/11 -- 6:38 AM -- According to the Lake Oswego Police Department, Ben McLemore was accused of committing the sex crimes in October 2021.

Cops say a woman told them McLemore -- who was a Portland Trail Blazer at the time -- sexually assaulted her while at a home in Lake Oswego.

Police added a grand jury formally indicted McLemore in February.

Former Kansas University men's basketball star Ben McLemore was arrested this week and booked on a charge of first-degree rape, TMZ Sports has confirmed.

Jail records show the 31-year-old -- who played in the NBA from 2013 through 2021 following his Jayhawks career -- was taken into custody in Multnomah County, Oregon on Tuesday on an outstanding warrant. He was later transferred to Clackamas County Jail on Wednesday.

Records show he remains behind bars there ... as he's facing one count of unlawful sexual penetration and two counts of sexual abuse -- in addition to the rape charge.

Further details on the allegations surrounding McLemore were not made immediately available ... although more is expected to be released later Wednesday -- after the basketball player is arraigned in court.

McLemore was a superstar for KU in his one season in Lawrence -- helping lead the Jayhawks to the Sweet 16 in 2013. He went on to be picked by the Sacramento Kings in the first round of the 2013 NBA Draft.

In his career, McLemore logged minutes for Sacramento, Houston, Portland, Memphis and the Los Angeles Lakers. Following his career, he went on to play overseas.