Amid rumors of friction between the two artists, Jay-Z [ tickets ] and R. Kelly [ tickets ] announced on Sunday (10/24) that they were scrapping two shows on their current "Best of Both Worlds" tour.

Citing "technical problems," the duo canceled its Sunday (10/24) show in Milwaukee, and its Tuesday (10/26) show in Hartford, CT. Ticket holders can obtain refunds at the point of purchase, according to organizers.

"The artists want to apologize to everyone who bought tickets to the Milwaukee and Hartford shows," a tour spokesman said in a statement. "They are as disappointed as anyone that they won't be able to perform as scheduled. These concerts are extremely complicated stage shows with a multitude of special effects, dance numbers, and lighting and sound cues, and unfortunately we need to take a few days off to work out some technical problems."

The cancellations followed Saturday's (10/23) show in St. Louis, which was a rocky experience for Kelly, according to the St. Louis Post-Dispatch.

According to the newspaper, at one point in the show, Kelly "stepped into the crowd and walked to the rear of the arena floor, where he got into a heated argument near the soundboard, all captured on the video screens. When Kelly got back to the stage, he took a bow and wasn't seen again."

Kelly's exit reportedly came well before the scheduled end of the show.

The newspaper also noted that Jay-Z and Kelly "shared only about 15 minutes of time on stage," and that they "never addressed each other and didn't appear to look at each other."

The tumultuous St. Louis show took place two days after the New York Daily News published in its Rush & Molloy gossip column a quote attributed to a "well-placed source" who claimed that Jay-Z and R. Kelly are not speaking to each other offstage.

Kelly's spokesman told the paper that the rumors of a feud are unfounded.

The tour is scheduled to resume on Thursday (10/28) at Nassau Coliseum in New York.

Jay-Z and R. Kelly were originally due to tour together following the 2002 release of their first collaborative album, "Best of Both Worlds," but those plans were scuttled after Kelly was charged with multiple counts of child pornography. The singer had to gain permission from a judge to embark on the current tour.

On Tuesday (10/26), Jay-Z and Kelly issue a follow-up to their 2002 debut. Titled "Best of Both Worlds: Unfinished Business," the set houses 11 tracks, including the singles "Big Chips" and "Don't Let Me Die."