Kang Jung-ho, Korean infielder for the Pittsburgh Pirates, is being investigated over a sexual assault allegation that emerged in Chicago, a U.S. newspaper said.

Citing a police spokesman, the Chicago Tribune reported Tuesday (local time) that Kang faces the probe over an incident that allegedly took place when the Pirates were visiting the Chicago Cubs last month. Kang hasn't been charged with a crime.

The Pirates said they are aware of the allegation and vowed full cooperation with the authorities.

"We take allegations of this type extremely seriously," Pirates President Frank Coonelly said in a statement published on the Chicago Tribune's website. "Pursuant to the Joint MLB/MLBPA Policy on such matters, this matter is exclusively before the Commissioner's Office at this time. We have and will continue to cooperate fully with the Commissioner's Office."

Coonelly added the Pirates won't make further comment due to the ongoing police investigation.

According to police, a Chicago woman met Kang through a dating app, and the ball player invited her to his hotel room on June 17, hours after the Pirates' loss to the Cubs in a day game. The woman's identity is being withheld because she is an alleged victim of a sex crime.

The woman told investigators she arrived at Kang's room at 10 p.m., and he gave her an alcoholic drink. She said she blacked out some 15 to 20 minutes later, and drifted in and out of consciousness as he sexually assaulted her.

She said she did not fully awaken until she was in a taxi and on her way home, according to police.

The woman, 23, went to a local hospital to have a rape kit on June 19 and filed a formal complaint with police 10 days later, according to the newspaper.

MLB told the Chicago Tribune in a statement that it will "monitor the progress of this investigation closely and will respond fully as additional facts emerge."

Kang, who joined the Pirates before the 2015 season on a four-year, $11 million deal, finished third in the Rookie of the Year voting last season with a .287 batting average, 15 home runs and 58 RBIs in 126 games. His season was cut short in mid-September after he suffered serious leg injuries on a hard slide by the Cubs' Chris Coghlan trying to break up a double play.

The Pirates will visit the Cubs this weekend. In August last year, Major League Baseball and the Major League Baseball Players Association agreed on a joint domestic violence, sexual assault and child abuse policy, in the hopes of deterring future violence, promoting victim safety and fostering an approach of education and prevention.

Under the agreement, there is no minimum or maximum penalty for violators as decided by the MLB commissioner.

MLB Commissioner’s Office will investigate all allegations of domestic violence, sexual assault and child abuse involving members of the baseball community. The accused player may be placed on paid administrative leave for up to seven days during the investigation.

Three players have been punished under the policy, all of them for domestic violence incidents: New York Yankees reliever Aroldis Chapman (30 games), Atlanta Braves infielder Hector Olivera (82 games) and veteran shortstop Jose Reyes, who was banned through May 31 this year and later released by the Colorado Rockies.

Kang returned to the majors in early May. He started off hot but has since cooled off. Kang was held out of the starting lineup against the St. Louis Cardinals on Tuesday in St. Louis but hit a single off the bench in the top of the ninth.

He entered the game batting just .111 with no home runs or RBIs over his previous seven games.

For the season, Kang is batting .255 with 11 home runs and 28 RBIs in 49 games. (Yonhap)