McDonald's has apologised for playing an explicit rap song which featured lyrics about underage sex and rape in one of their restaurants.

As the Western Telegraph reports, the track 'Only 17' by Rucka Rucka Ali was played to customers in the fast food's Haverfordwest branch. The track, which comes from rapper, comedian and satirist's 2011 album 'Probably Racist', includes lyrics such as "I fucked up my life, her butthole was tight/ But not worth doin' time, cause now I'm getin' boned in mine".

McDonald's customer Steve Davidson was eating in the restaurant with his 20-month-old grandson when the track was played. He said: "The bottom line is that it's bordering on pornography. It certainly shouldn't be playing in a restaurant where they sell Happy Meals to children.

"The lyrics are disgusting, they are very explicit – not just a bit risque or a bit of swearing. It's not what you want while you're having your breakfast. You have to be over 18 to download it, for them to be playing it somewhere that attracts children is obviously a concern."

According to McDonald's, the song was played by accident after an employee connected their personal music player to the restaurant's sound system during the night shift, and then forgot to remove it the following morning. "We offer our sincere apologies to Mr Davidson for any offence caused by the music playing in our Haverfordwest store last Friday morning," a spokesperson said. "The content and lyrics were wholly inappropriate and had no place in McDonald's."

The spokesperson, who also said that management had "spoken to the crew member involved", added: "McDonald's is a family-friendly restaurant and we endeavour to provide a restaurant environment that is welcoming, comfortable and enjoyable for everybody.

"The vast majority of our restaurants, including Haverfordwest, have external music providers dedicated to creating playlists that have been thoroughly screened for appropriateness of language and content. We apologise to Mr Davidson for this isolated lapse in our rigorous standards."

However, Rucka Rucka Ali has also now demanded an apology from McDonald's for playing the song, which is a parody of the Nelly track 'Just A Dream', without his permission. "Why doesn't McDonald's apologise to ME?" he wrote on his Facebook page. "My music is played at their restaurant without my permission!! Gimme some free cheeseburgers Ronald!!"