Eminem has been called "disgusting" and "pathetic" after rapping about the Manchester Arena bomb attack, which killed 22 people in 2017.
The lyric comes in a new song, Unaccommodating, in which the star boasts about his impact on hip-hop.
At one point, he says: "I'm contemplating yelling 'bombs away' on the game / Like I'm outside of an Ariana Grande concert waiting."
It is not the first time the 47-year-old has referenced the attack.
In a 2018 freestyle, he rapped about a brainwashed suicide bomber "seeing Ariana Grande sing her last song of the evening / And as the audience from the damn concert is leaving / Detonates the device strapped to his abdominal region."
Figen Murray, whose son died in the attack, voiced her disapproval after being informed of the two songs on Friday morning.
"Feels like he is piggybacking on the fame of Ariana Grande and Justin Bieber and says distasteful things about other celebrities," she wrote on Twitter.
"Not clever. Totally pointless. And before all Eminem fans pounce on me, I am not interested and will not engage."
Murray's 29-year-old son Martyn Hett was one of the 22 people who died when Salman Abedi blew himself up at the end of Ariana Grande's concert in May 2017.
She has since campaigned for the introduction of Martyn's Law, which would require venues to introduce more stringent security checks.
Hett's former partner Russell Hayward also voiced his disapproval of Eminem's latest lyrics, writing: "It's disappointing but not surprising that #Eminem would use controversial lyrics about the Manchester bomb, dragging the victims' families & Ariana back into a very dark time.
"Not sure how popular he is these days but I hope any success he gets from the back of this is worth it."
His comments were echoed by Grande's fans, who described Unaccommodating as "a pathetic attempt to get attention".
One fan tweeted the rapper saying: "You're so disgusting I hope u know that. What u said was very uncalled for and so hurtful to so many people."
The lyric feels particularly egregious, given that Eminem pledged his support to victims of the bombing in 2017; and urged fans to donate money to families who had been affected.
A follow-up to 2018's Kamikaze, the 20-track album features cameos from Q-Tip, Ed Sheeran and the late Juice Wrld.
In a stark contrast to the Manchester Arena lyric, the album's lead single, Darkness, advocates tighter gun control laws in the US.
The song and video reference the 2017 Route 91 Harvest music festival shooting in Las Vegas, in which 58 people died, with Eminem playing the role of an isolated, mentally-disturbed character who plots a murderous rampage to gain notoriety.
The video ends with a montage of news reports from recent mass shootings, captioned: "When will it end? When enough people care."
Eminem then urges fans to register to vote in the upcoming US elections, writing: "Make your voice heard and help change gun laws in America".
The video also links to a website with information and links to various anti-gun violence organisations including Everytown For Gun Safety, March For Our Lives and Sandy Hook Promise.
It is not the first time the star has addressed the issue. Performing at last year's iHeartRadio music awards, he delivered a verse attacking the National Rifle Association's hold over politicians, rapping: "They love their guns more than our children."
At the time of writing, he had not responded to the criticism over Unaccommodating. The BBC has contacted his publicists for comment.