Some would argue that glamorising violence in hip-hop is nothing new, but Omar Hammami, perhaps the world's only jihadist rapper, takes the genre to a whole new level.

With songs such as Send Me a Cruise (Missile) and Make Jihad with Me, the Alabama-born Hammami's notoriety has led to the US state department putting a $5m (£3.3m) bounty on his head. Not that Hammami – also known as al-Amriki, or "the American" – is letting it get him down.

On Thursday he took to Twitter to joke: "As I'm a bit low on cash, how much is my left leg going for? I figure Shamil Basayev [leader of the Chechen rebel movement] did the one-leg jihad thing."

Hammami, 28, went to Somalia to join the al-Qaida-linked al-Shabaab group in 2006 and the state department said he began recruiting for the jihadist cause through his English-language rap songs and videos. His voice has been described as "a deep Barry White growl".

But it is not just his music that has riled the US authorities. Hammami is believed to have fought for al-Shabaab in Somalia against the US-backed government. He was added to the FBI's list of most-wanted terrorists in November last year, the agency describing him as "armed and dangerous".

In 2007, he was charged in Alabama with providing material support to terrorists. Two years later new charges were filed against him for leaving the US to join al-Shabaab, which was labelled a foreign terrorist organisation by the state department in 2008.

Earlier this year Hammami released his autobiography, The Story of an American Jihadi, which, like his music, received less than flattering reviews. The Christian Science Monitor described it as a "strange mixture of childish humour (he writes "ha ha" a lot to indicate something he found funny) and deadly serious description of his life with al-Shabaab".

Hammami spilt from al-Shabaab last year, with the terror group denouncing his statements and actions as motivated by the "narcissistic pursuit of fame and … far removed from the reality on the ground". Amid the fallout, he was also accused of possibly the worst crime a rapper can be accused of, aside from terrorism: that of not writing his own rhymes.

Al-Shabaab now wants to kill him, but Hammami seems relaxed at the prospect of having groups on each side of the "war on terror" after his head. On Friday he joked on Twitter: "If being wanted dead by both US and Shabaab has something to do [with] my patchy beard, fake beards are something negotiable."