Kurdish fighters have found an unlikely ally in US rapper Nelly.

The hip hop star has become the first American to perform in war-torn Kurdistan after taking to the stage at a charity concert in Erbil to benefit troops battling terrorist group Islamic State (Isis) in northern Iraq.

The Hot In Here hitmaker made a surprise appearance at the show put on for Kurdistan's unofficial military, the Peshmerga, by the Rwanga Foundation, a non-profit organisation created to help those in the area.

According to the charity foundation, the concert aimed to "celebrate the people of the city, promote peace and bring hope to those who need it most" while also raising money for "those impacted by the recent conflict in the area".

Nelly, who was reportedly paid a six-figure appearance fee, said he was honoured to entertain troops at the event. The 40-year-old star performed alongside Arab Idol's Ammar Koofe and motocross star André Villa.

"I'm honoured that this country has basically paid attention to Nelly. Everybody has been so gracious and the hospitality has been first class. How could you not want to come back to a place where people show you so much gratitude and they're happy to have you," Nelly told Sky News.

But not everyone was happy about his appearance, with many critics lambasting the Rwanga Foundation for giving Nelly an impressive payday rather than giving the money directly to displaced families and troops.

Nelly appears to have been the last-minute replacement for fellow recording artist Akon, who had been set to headline the concert before bowing out for unknown reasons.

Earlier in March, Akon couldn't hold back his excitement when he announced his gig in a video, telling fans: "I am so excited to be there to visit that 8,000-year-old city to perform live at the Hariri Stadium in March."

But on Sunday (8 March) the foundation revealed that "Akon has cancelled for personal reasons but hopes to visit Kurdistan in the near future."