An Iranian rapper has become "the Salman Rushdie of music" after clerics in the Islamic republic issued fatwas calling him an apostate, which is considered punishable by death under the country's sharia law.

Shahin Najafi, a Germany-based Iranian singer, recently released a song with references to Ali al-Hadi al-Naqi, the tenth of the 12 Shia Muslim Imams, a religious figure highly respected by millions in Iran.

The controversial clip posted on Youtube, watched by hundreds of thousands online, has divided opinions in the country with many finding it offensive and insulting to their beliefs and others defending the song, saying it broke taboos especially in regards to expressing views about religious personalities.

When asked for a religious ruling on the fate of Najafi and his "blasphemous music", clerics unanimously declared that such a person must be considered an apostate.

According to the semi-official Mehr news agency, Ayatollah Naser Makareme Shirazi, a pro-Iranian regime cleric based in the holy city of Qom with a great deal of influence among Muslims in the country, was the latest person to issue a fatwa in regards to Najafi.

"Any outrage against the infallible imams ... and obvious insult against them would make a Muslim an apostate," he said. Makareme Shirazi has in the past issued other controversial rulings, including those against women attending football matches, keeping pets and the Holocaust.

Najafi's song, called Naqi, is a chronology of events in the past year. Najafi, 31, has rejected claims that he meant to insult people's religious beliefs, though the song criticises Iranian society.

"I thought there would be some ramifications. But I didn't think I would upset the regime that much. Now they are taking advantage of the situation and making it look like I was trying to criticise religion and put down believers," he told the Germany broadcaster Deutsche Welle.

"For me it is more of an excuse to talk about completely different things. I also criticise Iranian society in the song. It seems as though people are just concentrating on the word 'imam'."

Meanwhile, an Iranian religion website which runs on the regime-controlled .ir domain, Shia-Online.ir, has offered a $100,000 (£62,000) reward for anyone who kills Najafi.

"A (website) founder who lives in one of the Gulf Arab states has promised to pay the ($100,000) bounty on behalf of Shia-Online.ir to the killer of this abusive singer," the site said.

The fury surrounding Najafi and his work is reminiscent of the fatwa against Salman Rushdie whose novel, The Satanic Verses, brought him a death sentence by the founder of the Islamic republic, Ayatollah Ruhollah Khomeini in Iran.